GTM#534 wiring and Haltech

[ohmygosuness]

I'm about to start wiring up the car in the coming week or 2 and hopefully get it started. I'll have a bunch of general wiring questions (may or may not be Haltech related) so I think it deserves its own thread. I know someone else in here (rolfer) is using the same ECU as me (the Rebel LS) and maybe he could kindly chime in.

From researching Haltech's manual and videos, it seems really really straight forward. But since this is my first project car, I know I'll get stuck somewhere. And of course, if it's purely Haltech wiring related, I'll likely contact their tech support instead of posting on here.

Question #1 (not really related to wiring, LOL) - I have the water pump hooked up to heater core on the vintage air. Should I attempt to start the engine with heater core hooked up while A/C isn't running?

Question #2 - I need help decoding some wire colors on my driver side fuel pump (came from driver side on the Corvette, will be passenger side on the GTM). I know one of them should be the pump itself and the other one is for fuel leveler. But I don't know which one (this is from my C6 donor but may be similar to C5).

White (ish) - ?
Black - ground?
Dark Grey (thicker gauge than black) - 12V maybe?
Blue - fuel level?

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[beeman]

Right half of this image seems to match your connector

https://www.corvetteforum.com/forums/c6-tech-performance/4066657-need-a-wiring-diagram-right-fuel-tank-harness.html
https://cimg5.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/1267x558/left_tank_harness_connector_58b2e7c716744601e7eec0 f64546b51ff0fd7e5b.jpg
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[ohmygosuness]

Right half of this image seems to match your connector

https://www.corvetteforum.com/forums/c6-tech-performance/4066657-need-a-wiring-diagram-right-fuel-tank-harness.html
https://cimg5.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/1267x558/left_tank_harness_connector_58b2e7c716744601e7eec0 f64546b51ff0fd7e5b.jpg
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Thanks Beeman. That helped clarify some things. I assume the fuel leveler itself doesn't need power and it just sends a low voltage signal (dark blue wire) to the fuel gauge?

[beeman]

Thanks Beeman. That helped clarify some things. I assume the fuel leveler itself doesn't need power and it just sends a low voltage signal (dark blue wire) to the fuel gauge?

Fuel level senders typically are based on a resistance to ground, no voltage involved on the sender side.

[beeman]

I have the water pump hooked up to heater core on the vintage air. Should I attempt to start the engine with heater core hooked up while A/C isn't running?

not sure what you are asking here, I am assuming you have filled the car with coolant and are worried about air trapped in the heater core? With modern cars, you are told to turn the heat on while burping cooling systems so that any coolant shutoff valves to the heater core are opened by the HVAC system. If you are running a manual or electric/solenoid shutoff valve to your heater core, make sure it is open and the lines are higher than the core so it can bleed. If you are only doing a quick diagnostic startup of the engine, you don't need coolant...

[crash]

If you are only doing a quick diagnostic startup of the engine, you don't need coolant...

I see people on You Tube do engine start ups all the time with no coolant and I cringe. If it is for a few seconds to see how things are operating, fine, but anything more than a few seconds of run time and I would highly recommend against it.

As beeman said, just make sure there is fluid flow when initially burping the system. I can tell you that my experience is that the LS water pumps trap air and I put a gas release tube on all my builds now because even with the header tank system, air can get trapped inside the water pump causing cavitation and lack of water flow. We used to have to cycle the engine on and off a few times to get this air out of the water pump. I put the bleed lines in and this need has gone away. Point is, you may have to start and stop the engine a few times to get all the air out, even if the system is set up properly with a high point for the air to collect at.

[ohmygosuness]

I haven't done too much on the A/C yet other than hooking up the hoses. But it sounds like I need the A/C somewhat powered so the heater valve is open?

Crash - I don't know what youtubers are saying, but I probably wouldn't attempt to start the car without coolant. Not even for a second :D

[rolfer]

If you have any other questions about the fuel pump/level sensor let me know. I just finished hooking all that stuff up on my car.

It is pretty straightforward, the pump need power and a ground. The sensor need a sensor ground and you have a signal wire and that is about it.

One thing I did was put a high amp, sealed, one pin connector on the power wire right near the ecu for the pump. It is an easy way to cut off the pump if you need to.

You can also turn off the fuel pump from your phones haltech app.

[ohmygosuness]

If you have any other questions about the fuel pump/level sensor let me know. I just finished hooking all that stuff up on my car.

It is pretty straightforward, the pump need power and a ground. The sensor need a sensor ground and you have a signal wire and that is about it.

One thing I did was put a high amp, sealed, one pin connector on the power wire right near the ecu for the pump. It is an easy way to cut off the pump if you need to.

You can also turn off the fuel pump from your phones haltech app.

I'm assuming the sensor has its own ground? Not sharing the same ground wire with the pump. In my case, I think it may be the "low reference" wire.
Are we putting a fuse for each component? (going through a fuse box or a fused connection?)

By the way, are you using a Gen III or Gen IV LS?

[rolfer]

Yes the sensors and gauges usually have their own separate grounds sometimes referred to as "low reference".

The rebel has 4 - 25 amp outputs. one for the fuel pump, one for the coolant fans, one for stater solenoid and one you can use for what ever you want. You can program the outputs to control other things if you would like they are not dedicated.

haltech does not show putting fuses inline for these outputs so I presume they are internally fused.

I am running a Gen IV LS.

One thing is the harness is made for a front engine car so I had to extend the drivers side knock sensor wiring and the air temperature sensor as well. I did shorten a lot of wires as well but that is a lot easier and you are going to have to modify any wiring harness for the GTM.

If you have any questions do not hesitate to call them up. One big reason I went with them is their product support has been excellent which goes a very long way with me.

[crash]

The rebel has 4 - 25 amp outputs. one for the fuel pump, one for the coolant fans, one for stater solenoid and one you can use for what ever you want. You can program the outputs to control other things if you would like they are not dedicated.

haltech does not show putting fuses inline for these outputs so I presume they are internally fused.



I am not familiar with the current Haltech offerings, but if this Rebel unit has on board power distribution unit capabilities, which it sounds like it does, then there is likely a screen in their software where you can set amp thresholds for each channel. The electronics would then monitor the amp flow and cut the power if it exceeds what you program. This is one of THE best things about using a PDU is that you can precisely change your "fuse" settings and the amp draw rates are constantly monitored, and in many cases logged, so you can see when an electrical load item is going bad.

[ohmygosuness]

If a fuse box won't be used then it would save a bit of room.

rolfer - Are you going to be using the EVAP canister, vent solenoid, air purge stuff?

[beeman]

This is one of THE best things about using a PDU is that you can precisely change your "fuse" settings and the amp draw rates are constantly monitored, and in many cases logged, so you can see when an electrical load item is going bad.

Yes that is definitely a cool feature. But I'd still rather have my amperage through a $3 relay than a $1500 ECU.

[ohmygosuness]

Yes that is definitely a cool feature. But I'd still rather have my amperage through a $3 relay than a $1500 ECU.

I know exactly what you mean. I have thought about adding fuses for an extra line of safety. Wouldn't hurt, right?? :D

[crash]

Yes that is definitely a cool feature. But I'd still rather have my amperage through a $3 relay than a $1500 ECU.

To your point, I do not use a PDU in the FFR PDG GTM. While the data is a nice feature I feel the old school relays and medium amp individual switches are easier to fix on the fly...and cheaper...both upfront and in repairs. That said, if I already had the capability via a PDU as part of an ECU then I think I would set the PDU up to be kind of a "main bus" type of deal and then run fuses/breakers also. This gives you the repair point of the analog solution along with the data of the digital solution. If this ECU really has 4 X 25amp channels...100 amps can do quite a bit. There are some really nice features to PDUs but, so far, I have resisted in deference to reliability...and cost.

[rolfer]

If a fuse box won't be used then it would save a bit of room.

rolfer - Are you going to be using the EVAP canister, vent solenoid, air purge stuff?

no my engine is no where near factory and I just have to pass a safety test.

[ohmygosuness]

Do any of you guys use an in-line fuse going from battery to power the starter motor (not solenoid)? I'm getting mixed results from researching. Apparently, the starter would be pulling >250A but my 1/0 battery cable allows ~150A. Doesn't seem to make sense to have a fuse there. I'm thinking of having a 30A in-line fuse from key switch to start solenoid and that's it.

[beeman]

Do any of you guys use an in-line fuse going from battery to power the starter motor (not solenoid)? I'm getting mixed results from researching. Apparently, the starter would be pulling >250A but my 1/0 battery cable allows ~150A. Doesn't seem to make sense to have a fuse there. I'm thinking of having a 30A in-line fuse from key switch to start solenoid and that's it.

Technically, that would be a fusible link rather than a fuse.
I haven't used one in any builds.

[crash]

It's a big ask and risk to have anything that can "blow" on the starter cable. A momentarily stalled starter motor can leave you without the ability to start your engine. (Of course you could always push start a GTM)

On the other hand, with the cable running near or even through the cabin and having a bunch of areas that could be pinch/wear points in an "incident" it would be bad to have someone hurt or the car burn down.

We use a heavy gauge "welding cable" for both the starter and ground wire that run front to back. I have thought about putting an extra couple layers of heat shrink protection on them but have not had any issues yet as they are protected and glued in place where they cross thru any sheet metal. This was done by using PVC electrical pipe ends held into the sheet metal, feeding the wire thru and then filling the conduit with silicone or the like. The cable is in split loom and held down with adel clamps in other places. I do not run them bundled with other wires.

It is definitely something to worry about but in my opinion, I am not going to use a fusable link on the starter cable.

[VRaptor SpeedWorks, LLC]

I agree with Crash on that one. I always run the split corrugated wire loom along the whole length of the cable and am very careful where I route it so that there's nothing that it can really rub on or vibrate against.

This is one area where I see a lot of builders who obviously don't understand the risks involved. I've worked on a lot of GTM's where this cable is completely unprotected and unsecured.....then ran up to the main post on the donor Under Hood Fuse Box....and a bunch of other wires stacked on top of that post and ran out to power other stuff throughout the car. Every single one of those wires is unfused power....and all it takes is one of those wires to wear thru or get pinched and the whole car burns to the ground. And yes.....we've seen multiple GTM's burn to the ground that I'm aware of on this forum and facebook. I'm sure some of those are also fuel related.....but I would bet that 90+% of the cars that burn down are due to an electrical short.

[ohmygosuness]

I agree with Crash on that one. I always run the split corrugated wire loom along the whole length of the cable and am very careful where I route it so that there's nothing that it can really rub on or vibrate against.

This is one area where I see a lot of builders who obviously don't understand the risks involved. I've worked on a lot of GTM's where this cable is completely unprotected and unsecured.....then ran up to the main post on the donor Under Hood Fuse Box....and a bunch of other wires stacked on top of that post and ran out to power other stuff throughout the car. Every single one of those wires is unfused power....and all it takes is one of those wires to wear thru or get pinched and the whole car burns to the ground. And yes.....we've seen multiple GTM's burn to the ground that I'm aware of on this forum and facebook. I'm sure some of those are also fuel related.....but I would bet that 90+% of the cars that burn down are due to an electrical short.

That's one of my greatest fears! All the blood, sweat, tears, poured into this build wasted because of something shorting out. I'm going to put a fuse where ever I can. I also called Haltech tech support and he said it's not recommended to fuse anything going in/out of the ECU. I'm still feeling a bit conflicted about that. I did get some 1/0 welding cables for the starter and alternator, they will be routed individually. Will definitely be wrapping each wire thicker than 4 AWG like xmas presents.

When I first started the build, I hear people talking about issues with not having enough space running hoses/wire from the front to back of the car. Now that I've put most things in place, I'm starting to see that being a real issue. There's pretty much no room left for me to run anything to the back going around the A/C compressor side at least.

[ohmygosuness]

Technically, that would be a fusible link rather than a fuse.
I haven't used one in any builds.

Beeman,

I received the Braille battery. Also got a charger for it. This thing is tiny! Thanks for the recommendation. It fits good.

[crash]

Here's a picture where you can see how the wires go through the front sheet metal on the FFR PDG GTM. You might need to zoom, but you can see that each cable goes through it's own sheet metal isolator and all other wires have mil spec plugs.

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[ohmygosuness]

Here's a picture where you can see how the wires go through the front sheet metal on the FFR PDG GTM. You might need to zoom, but you can see that each cable goes through it's own sheet metal isolator and all other wires have mil spec plugs.

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I think I've said it before but one thing I love about the race car is how it looks like it's been driven hard and how practical everything is.

Do you have one big cable, coming off the battery, that branches off later? Or is there more than one cable in that corrugated flex hose on the positive terminal? A bit hard to tell.

[crash]

There is only one thing on the main cable to the starter, and that is the race sanctioning body required main shut off switch. So the cable goes to the switch, which is large and I have never had an issue with as far as current handling for the starter, and then on the switched side where the cable continues to the starter there is a bunch of main wires that go to various places, such as the main fuse panel, the electric A/C fuse panel, and the ABS fuse panel. These are all short runs under the dash from the main power switch to the various fuse panels.

The one thing that is on the race car that you would likely not have is this switch, and a requirement that when turned off, the engine must stop. There is an issue with the alternator charge feed in that it will loop back and continue to allow the engine to keep running even if the battery is isolated and removed from the equation, so I run a large continuous duty 300 amp golf cart solenoid on the charge line that gets opened if the main power switch is tripped, so there are some big switches on the main line on the race car, but you should not have to worry about those.

I think the way I would do it is to run a straight uninterrupted line from the battery positive to the starter and make sure it is insolated, protected, and attached to the frame in a "bullet proof" fashion, and then run another, something like 10 or 8 gage, main wire from the battery positive to your main distribution block or fuse panel. If it goes to a distribution block and/or runs any length where it is unfused, then I would run a large fuse or fusible link on this line. Fusible link would be best as it could go very close to the connection to the battery in an inline fashion. You should calculate what is required here, but I would leave a good margin to the up side so it never trips unless it is something catastrophic. Again, you want to avoid being stuck somewhere just because one of your loads has a problem of some sort.

[ohmygosuness]

I was testing my radiator fan. Like most other electricals, it should've been one of the easier things to wire since it should work on only 2 wires (12V and ground). So I plugged it up, didn't run. But since this is a C6 radiator fan and it comes with a 3rd wire for 'speed control.'
(I think the C5 only has 2 wires - red and black).

I also haven't charged my battery since I got it. I'm charging it now hoping it's just low on battery. Otherwise, do I do anything with this 'speed control' wire?

Edit: Now that I think about it, do you guys run your fan on full blast when the coolant reaches a certain temp or do you have it on variable speeds to save power?
Edit: I also tested the power to ground with a meter to make sure 12v is hot and ground is good. So, I'm sure there's no issue with my connections.

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[crash]

Just my opinion on how to trouble shoot this...get some jumpers to the battery directly. See how to make the fan run with direct 12 volts from battery. Once you figure out what the fan needs, then get the outputs from the ECU to correspond. There is probably a wiring diagram available online for the C6 fans.

I use the C5 fans at full speed on or off.

[VRaptor SpeedWorks, LLC]

Edit: Now that I think about it, do you guys run your fan on full blast when the coolant reaches a certain temp or do you have it on variable speeds to save power?


217035

For me, it all depends on how I'm controlling the fans. When using the donor C5 ECU, I wire up the fans in the same way as factory so that the ECU controls the fans....Off, low speed (fans wired in series) and high speed (fans wired in parallel) thru the same relay connections as the C5. This is the easiest way, since the ECU can also control the fans for AC use in the same way as the C5.

If using an aftermarket fan controller, I wire it however the fan controller dictates....which is usually just On/Off.

[ohmygosuness]

I thought I could just have it on full blast the whole time without the need for speed control. The wire diagram on the C6 does say the third wire goes to the ECU. But I don't know if it's necessary to control the speed other than to save some battery power. I might rip out the control module for the radiator fan (can be seen in the above pic) and see if it runs on/off mode.

Since I have the power going through the control module, It's also possible that the fan isn't turning on because it hasn't reached a certain coolant temps and it's waiting for that signal from the ECM.

[crash]

I don't know the particulars of the Haltech ECU. I think the fan module is redundant if the ECU has the ability to control fans by temp sensor input. On the other hand, the ECU output is probably not a high amp output and so a relay would need to be put in line on the fan power and then that controlled by the ECU fan output. It looks like the fans are still two wire, but the controller is what you are saying is three wire? My suggestion is...ditch the controller(just more electrics to go wrong) use the fans as two wire on/off units and let the ECU control the on/off function via appropriate sized relay.

[rolfer]

If it is a rebel LS then it does have a 25A output for fans. You can also hook up the control wire to a PDM output to have variable speed fans.

[ohmygosuness]

If it is a rebel LS then it does have a 25A output for fans. You can also hook up the control wire to a PDM output to have variable speed fans.
Yea it's the rebel LS and the fan is currently hooked up to the 25A output. I might have to call them up to have them help me setting up the output for variable speed or just do what crash suggested. I want to try and start the car to troubleshoot any leaks. I might just use my garage fan for now lol.

[rolfer]

I have found haltech tech line to be very helpful.

[crash]

It should be noted that the fuse in the given wiring diagram is either a 50 or 60 amp rated fuse.(I can't tell which because it is blurry) That seems a bit high for just the two fans, but you will need to determine the current draw of the fans before deciding whether to hook them up direct to the ECU or not. I probably would not risk damaging the ECU and would just put a relay in.

[ohmygosuness]

It should be noted that the fuse in the given wiring diagram is either a 50 or 60 amp rated fuse.(I can't tell which because it is blurry) That seems a bit high for just the two fans, but you will need to determine the current draw of the fans before deciding whether to hook them up direct to the ECU or not. I probably would not risk damaging the ECU and would just put a relay in.

Thanks for pointing that out. The weird thing is the 2 wires from the motor looks like 12 ga that could handle maybe 20-25 amps. I'm feeling more skeptical now about running the fan through ECU. I might just run a power separately to the fan through a relay and have the ECU do a 12V output to the solenoid to control the shut off.

[Shoeless]

I bet current draw to start two of these fans simultaneously would work all of that circuit that has the 50 or 60 am fuse on it. I did not investigate the haltec documentation to confirm this, but if you want to go for what's in the diagram in post 29, just find a low side switched input that you can control for fan function in the ECU.

[ohmygosuness]

I ripped out the control module on the radiator this weekend and connected power output from Haltech directly to fan motor. Now fan turns on when ignition is on.
I think what I'll do next is to have Haltech turn on fan when coolant reaches a certain temp and/or when A/C is on. Not sure how I'm gonna go about that yet.

Do you guys have it so the fan keeps running until coolant temp drops, even after engine is off?

[Shoeless]

Do you have any experience in Haltech's tuning software?

I personally do not, but I'd bet it's not all that hard. There should be a fan trigger somewhere in the software that let's you choose the circuit you are using to switch the fans on and off and then set the temp turn on and cut off points.

If you have no desire to get in there and play with that, I'd find what ever tuner you plan to work with on this and let him/her get you set up to start.

[ohmygosuness]

I have the software installed but haven't played around with it too much. Will probably take a look when I get off work. If they have it built into the software then I'm sure it'll be easy. To turn on at a specific coolant temp. But for vintage air, I might need a relay to get the 12 V signal to turn on the fan.

[crash]

Did you use a relay? If not, hopefully the ECU has some internal safeties.

[ohmygosuness]

Did you use a relay? If not, hopefully the ECU has some internal safeties.
Haltech said this ECU is internally "fused." But I may still end up using a relay to turn fan on when vintage air is on. But then I might just do that through ECU inputs.

[VRaptor SpeedWorks, LLC]

Do you guys have it so the fan keeps running until coolant temp drops, even after engine is off?

Since the fan is only cooling the radiator, and not the coolant in the engine, the fan would probably continue to run until the battery was dead......

[Shoeless]

I'd like to provide a recommendation. You need to pause and find out what the Haltech ECU can and more importantly CAN'T do with respect to fans.

I say this as there is a possibility that the fan circuit that is internally fused might be the only circuit you can turn on and off with the internal temperature set points. Before you go adding an output to control a relay, low side switch BTW not +12V to trigger it, you need 100% confirmation that your ECU can do what you are asking it to do. I hope it can, it does seem like a simple function, but remember, the engineers on the other side of this could have easily said fans will always be connected to circuit x and there is no need to add the availability to control other circuits all on temp set points therefore what you want to do is not possible. It sounds stupid, and in all honesty, I hope it is, and this is a simple item to navigate. You could have the ability to create a 2D table with temps set points and fan on/off parameters and this is a complete moot point. I just don't know because I'm not familiar with the Haltec platform. I don't mind reaching out to a couple other people that I believe even went with a Haltec in their GTM. Either they did just the Dash or Dash and ECU. I'll report back.

In the MoTeC world, I can literally do ANYTHING :cool:. But they surely make you pay up to get that functionality LOL.

I'd hate for you to assume something can be done simply, and then you go build your engine harness, wire it all up, just to find out it might not be possible.

These are literally the things that kept me awake at night stressing out wondering if I crossed off every T and dotted every I.

[ohmygosuness]

You're right, Shoeless, to suspect that they have a dedicated wire/function for fans. This Haltec ECU came with a harness that literally has a wire labeled "fan." So, I'm going to only using that wire for my fan. The extra things I was planning on doing was just for the fan to turn on when AC is on (maybe through a relay). Which (from a phone call last night) they also have a function built into the software to do exactly that. Apparently, there's not much wiring I need to do on my own. Which I'm quite happy about with this ECU.

Honestly, now that I think about it, I may just have the fan on full blast for as long as the car is on. I probably won't even need the extra function to trigger fan when A/C is on since the fan will be on all the time.

[Shoeless]

I'm glad you were able to confirm on a call last night about the A/C trigger. That's something that every aftermarket ECU has to navigate, and I would assume it's not terribly involved to get that set properly.

You are on the right path here. You are tackling the problem and confirming the functionality you are looking for. Legit, go do this for every circuit coming out of that ECU now. Some are simple, 8 injectors, 8 coils, and then it just gets more involved from there. Like what is the calibration curve for the Engine Temp sensor you have? You better find out because you need to tell the ECU how to interpret the signal it receives from the sensor so that it's reading it properly. How about MAP sensor? I'm guessing you will be going Speed/Density tuning and won't need a MAF, but you need the calibration from that sensor. Thankfully some ECUs have standard items to choose from to assist in your set up.

Let the ECU control the fan. It's designed to do exactly that and once you set it up, it will work. Theres no need to have a fan on 100% of the time, unless we are talking crash and

This is the non-sexy side of wiring and tuning. LOTS of documentation and planning is 100% required to get this right.

[ohmygosuness]

Haltech does let you choose specific items from a list during the setup process using manufacturers' part # such as injectors, MAP, and some other sensors. Seems like most things are already setup in the software. I'll play around with the fan control a bit more when I get home.

[Shoeless]

Haltech does let you choose specific items from a list during the setup process using manufacturers' part # such as injectors, MAP, and some other sensors. Seems like most things are already setup in the software. I'll play around with the fan control a bit more when I get home.

That definitely helps. If they actually have calibration curves for everything you are using, that’s awesome. I can’t remember back when I first set my ECU up, but I definitely had to run down a couple calibration curves and manually create those.

[Shoeless]

While we are on the topic of your fans and A/C, you need to identify a HIGH SIDE OUTPUT (+12V) to send a “full throttle” signal to the Vintage Air to turn it off on high RPM runs. I believe I have mine set to 4000. Simple table in the ECU sends a +12V signal to the Vintage Air to shut it off at the set RPM.

[ohmygosuness]

Do you guys have any tips in hiding ugly wires hanging out?
Shoeless, I was looking at some of the pics you posted recently and I thought to myself damn that is a clean engine bay.
Right now I just have the wires kind of thrown on the engine. I lengthened all the necessary wires to fit this car. But now I need to cut some of them shorter and clean it up. Even then, I still don't see much room to tuck them and make it look nice and tidy. Would installing more aluminum panels help hide the wires a bit?
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[Ajzride]

Don't take shoeless advice on wiring unless you are ready to start from scratch and spend hundreds of hours and thousands of dollars on the task. He did a motorsport grade harness with spiral wound branches. Braided split loom can help a bunch with tidying up wires, but the best solution is going to be to buy some good crimpers and pin removers, and trim every wire the exact length it needs to be when routed cleanly, and re-crimp it. Then you can secure everything in loom or just zip ties to the frame/body.

[narkosys]

But if you do want to take a deep dive into his wiring, here is the link to his thread: https://thefactoryfiveforum.com/showthread.php?32017-Professional-Motorsports-Wiring-Harness-Venture

[beeman]

The braided split looms look so much better than the plastic loom.
https://m.media-amazon.com/images/I/71L3RuRFRXL.jpg

[beeman]

I really like these saddle cable tie mounts for fixing wiring to the chassis or panels. You can use a machine screw, but I prefer a simple 1/8" rivet. Super light and cheap.


https://m.media-amazon.com/images/I/61LRCf+bf9L._AC_SX679_.jpg

[ohmygosuness]

Don't take shoeless advice on wiring unless you are ready to start from scratch and spend hundreds of hours and thousands of dollars on the task. He did a motorsport grade harness with spiral wound branches. Braided split loom can help a bunch with tidying up wires, but the best solution is going to be to buy some good crimpers and pin removers, and trim every wire the exact length it needs to be when routed cleanly, and re-crimp it. Then you can secure everything in loom or just zip ties to the frame/body.

I'll take some advice from Shoeless and then scale it down a bit to match my time availability and financial capabilities LOL
I think I'll look into braided split loom. The corrugated ones I have is getting a bit too bulky. Also, I need to figure out where I want them routed.

[ohmygosuness]

But if you do want to take a deep dive into his wiring, here is the link to his thread: https://thefactoryfiveforum.com/showthread.php?32017-Professional-Motorsports-Wiring-Harness-Venture

I just looked over the first page and I already learned about the epoxy resin for buttons/sensors. Never knew something like that existed. I'll look into his thread a bit more.

[ohmygosuness]

I really like these saddle cable tie mounts for fixing wiring to the chassis or panels. You can use a machine screw, but I prefer a simple 1/8" rivet. Super light and cheap.


https://m.media-amazon.com/images/I/61LRCf+bf9L._AC_SX679_.jpg

I'm definitely getting those. I was looking for something like that but didn't know what to call them. Thanks.

[crash]

Good options here:

https://www.prowireusa.com/cable-tie-accessories

And these are the ones I use:

https://www.prowireusa.com/p-1174-1-cable-tie-mounting-pad.html

They are relatively cheap, and the adhesive allows you to direct the wires and keep them headed in that direction after you use a rivet to ensure the adhesive doesn't give up on the task. Also lets you attach the wires to square frame rails without using rivets if you are worried about maintaining strength in the tube the wires are now attached to. Many/most times I just use zip ties around the frame tubes to avoid the drilling holes in structural members issue. More industrial looking but super easy to get off and replace when needed.

[ohmygosuness]

Good options here:

https://www.prowireusa.com/cable-tie-accessories

And these are the ones I use:

https://www.prowireusa.com/p-1174-1-cable-tie-mounting-pad.html

They are relatively cheap, and the adhesive allows you to direct the wires and keep them headed in that direction after you use a rivet to ensure the adhesive doesn't give up on the task. Also lets you attach the wires to square frame rails without using rivets if you are worried about maintaining strength in the tube the wires are now attached to. Many/most times I just use zip ties around the frame tubes to avoid the drilling holes in structural members issue. More industrial looking but super easy to get off and replace when needed.

These are even lower profile! Nice. I was about to use small rubber hose clamps to tie cables. LOL. I'm so glad I posted here before doing anything.

[Ajzride]

On the 818 the Frame was thick enough to tap with 8-32 threads and then attach the zip tie saddles with a machine screw. Much easier to replace one if you break it versus having to drill out a rivit.

[Shoeless]

I can certainly adjust my recommendations based on the task at hand :D.

The rough 9 step process I outline on the Harness Build thread is totally applicable here, so I'll repost it (with changes for this effort).

1. Component Listing and Physical Location
2. Power Supply Design - Likely already done w the standalone ECU
3. Sensor Design
4. Grounding Design
5. Actuator Design
6. Material Selection
7. Harness Routing
8. Concentric Twisting - N/A
9. Construction Plan

Since you asked specifically how do I clean up the mess of wires everywhere, I'll focus on those steps. #7 is absolutely necessary as your next step, hopefully you have done everything before already. So what are we talking about here? In Post 107 on my Motorsports Wiring thread, you can see I use rope and physically create a mock harness with all the branch points and everything marked. You then remove this rope "harness" from the car and create a diagram. Doesn't need to be fancy, just accurate :cool:. Now you can measure out each individual circuit because you know exactly how long all the branches need to be to go from the ECU to the sensor or actuator or whatever it is. Then when you go to build it, you can get a large peg board from HomeDepot and physically measure out the whole harness and then essentially build it on the board circuit by circuit. Since this is considered a club level type harness this is the appropriate method of construction followed by covering with split loom and maybe some nice glue lined heat shrink at the ends to make it clean.

[crash]

I have to say that split loom is not my favorite, but I find it has it's place and I use it a lot.

Split loom is great for adaptability. You can add or remove wires easily and while the heat shrink on the ends looks good, I almost never use that in the way I use split loom. I simply use a small zip tie at the ends to ensure wires do not try and come out of the loom. This allows me to just snip the zip tie to add or remove wires. Once I have run the harness for a bit and am confident that everything is set, then I will remove the split loom and heat shrink the full loom. This is made much easier if you use Deustch connectors because if the heat shrink is too small to go over a termination connector, then you simply unpin the connector and the pins only should make the loom small enough to use the appropriate heat shrink tubing size.

I find split loom invaluable for getting things sorted, but feel the proper heat shrink covering is the final goal.

[ohmygosuness]

I can certainly adjust my recommendations based on the task at hand :D.

The rough 9 step process I outline on the Harness Build thread is totally applicable here, so I'll repost it (with changes for this effort).

1. Component Listing and Physical Location
2. Power Supply Design - Likely already done w the standalone ECU
3. Sensor Design
4. Grounding Design
5. Actuator Design
6. Material Selection
7. Harness Routing
8. Concentric Twisting - N/A
9. Construction Plan

Since you asked specifically how do I clean up the mess of wires everywhere, I'll focus on those steps. #7 is absolutely necessary as your next step, hopefully you have done everything before already. So what are we talking about here? In Post 107 on my Motorsports Wiring thread, you can see I use rope and physically create a mock harness with all the branch points and everything marked. You then remove this rope "harness" from the car and create a diagram. Doesn't need to be fancy, just accurate :cool:. Now you can measure out each individual circuit because you know exactly how long all the branches need to be to go from the ECU to the sensor or actuator or whatever it is. Then when you go to build it, you can get a large peg board from HomeDepot and physically measure out the whole harness and then essentially build it on the board circuit by circuit. Since this is considered a club level type harness this is the appropriate method of construction followed by covering with split loom and maybe some nice glue lined heat shrink at the ends to make it clean.

I was reading post#107 in your wiring thread and a couple more posts below that and the topic of crimping vs soldering came up (starting at post#112). It got me into an hour long rabbit hole researching on that topic. To make long story short, I'm going to start crimping as much as I can. I already modified the current harness through (mostly) soldering. I believe I will cut them all out and replace with either marine-grade butt connectors or open barrel crimp with shrink tube.

Also, did I mention I like the epoxy resin you used for sensors/buttons? I'll probably do that too. I'm wondering what type of consistency it has when dried. Is it stiff like clay? or rubbery?

Edit: I will also plan out the wire route with a rope or something (similar to what you did). Except, I think I don't have enough aluminum panels on yet to know exactly where I can route my wires. My next step could possibly be clico-ing up some panels to see where I can route them.

[ohmygosuness]

I have to say that split loom is not my favorite, but I find it has it's place and I use it a lot.

Split loom is great for adaptability. You can add or remove wires easily and while the heat shrink on the ends looks good, I almost never use that in the way I use split loom. I simply use a small zip tie at the ends to ensure wires do not try and come out of the loom. This allows me to just snip the zip tie to add or remove wires. Once I have run the harness for a bit and am confident that everything is set, then I will remove the split loom and heat shrink the full loom. This is made much easier if you use Deustch connectors because if the heat shrink is too small to go over a termination connector, then you simply unpin the connector and the pins only should make the loom small enough to use the appropriate heat shrink tubing size.

I find split loom invaluable for getting things sorted, but feel the proper heat shrink covering is the final goal.

Nice. I knew there's something better out there! I just didn't know what they were called. I work with some electricians at my job and they recommended these split-tube-looms so I went with it for now. But with this info in mind, I think I'll tear up my whole wiring setup and start from scratch.

Oh I love redoing stuff.

[crash]

Nice. I knew there's something better out there! I just didn't know what they were called. I work with some electricians at my job and they recommended these split-tube-looms so I went with it for now. But with this info in mind, I think I'll tear up my whole wiring setup and start from scratch.

Oh I love redoing stuff.

I think I may sense a tone of sarcasm? I am not saying you should not use what you have. Just saying how I use split loom all the time during the building and refinement process. The Deutsch connectors are very good connectors and more than adequate for performance automotive applications, but are not cheap.

If you followed Shoeless' journey on wiring you will see a top of the line automotive implementation of Tefzel wire and IIRC a mix of Autosport and Deutsch connectors, but, again, be prepared for time and cost if you go down this road. My last wiring harness just for the engine was around $5k. I did not build it myself and had to immediately take the cutters to it because the individual did not listen to my routing instructions for the knock sensors(that was a painful cut, but easily fixed the issue)so be prepared as I probably would have spent $3k-$4k in materials for that harness even if I did it myself.

I am guessing that if you do a full GTM with "the good stuff" that you would be looking at $10k-$15k if you did it yourself. Maybe Shoeless can verify what he estimates he spent?

BTW- Just the crimping tool for the Duetsch pins is a $300-$400 investment.

[crash]

That link I provided, https://www.prowireusa.com/ is the source I use for most of my connectors, wire, and heat shrink, but you can sometimes find some of the Deutsch connectors on Ebay at better prices. You just have to know specifically what you are looking for and make sure that is what you are buying on Ebay. The plug builder feature on the Pro Wire website I find to be a great time saver, so I use that source the most.

Also, you can possibly find some really good electrical components if you have a surplus electronics store near you. I once bought three $300 aircraft switches for $10 a piece. Didn't realize what they were and figured they might be a $50 aircraft switch based simply on how they looked. After I got home and googled them(a week later or so) I went back to the store to buy the rest of the box and there was nothing but an empty spot on the shelf. Anyway, point is that you can get some amazing stuff at super discounts if you are willing to shop around...and just get lucky sometimes.

I've found a lot of good switches on Ebay, but again, you need to know specifically what you want. Like part number and manufacturer type of specific.

[crash]

To add maybe just a little more to the conversation here...one of the reasons I did not do my engine wiring harness myself is because the engine has a lot of bespoke plugs on it. Not that you can't track down these plugs and/or pins to do the job, but that was one of the main reasons I went with a company that builds custom harnesses all the time. It was that they had the plugs that were needed to do the job and could turn around a finished engine harness quickly.

Again, if you go down this road you will need to find certain pins for certain sensor plugs, and then you may need to invest in certain crimping tools to make it all work. Depinning tools can be a challange also. I have made and improvised a few over the years.

Don't make the mistake of thinking a high grade wiring harness is something that is easy or budget friendly. As Shoeless discovered, it requires a lot of time, resources, and planning to come out right.

I suppose my recommendation to you, and to anyone really, is that unless you have a particular need for a high end harness, or you just want to learn a new skill and craft, what you have is likely adequate for a street focused GTM. Just make sure it is clean and tidy with no exposed connections and, yes, split loom is fine, and you should be good to go.

[VRaptor SpeedWorks, LLC]

Just to throw in my $.02.

The braided sleeve stuff the Beeman posted in #52......yes, I agree 100% that it's much more pleasing to look at. I really hate working with that stuff. I would estimate that it's going to take about 10x longer to install that stuff over the regular plastic split loom.

The split plastic loom.....the stuff that comes with the kit is low temp crap that will melt in the engine bay. You want the nylon stuff with the gray stripe on it....high temp and won't melt under normal conditions...if you decide to use any of that. The nylon split loom is all I use here (unless requested otherwise :D ). It's easy to install....easy to add or remove wires as Crash pointed out. IMO, for a street car, it's just fine.

Solder connections. Again....some may disagree, but solder with the heat shrink with the adhesive inside is all I've done here for almost 20 years. To my knowledge, out of all of the cars I've built, I have yet to have a customer call and tell me that one of my solder joints failed. No, I would not put a solder joint in the middle of a harness where there was going to be any considerable motion....like the wires between the chassis and door where the harness flexes every time you open and close the door. In almost every case in these cars, the solder joints end up in a place that has zero motion and is anchored to the chassis or just laying there in the tunnel with everything else. The heat shrink I use is very thick and rigid when it shrinks down, and extends past the solder joint on both sides.....so the heatshrink pretty well isolates the solder joint from any vibration or movement that might crack or break over time. Again.....in 20 years.....over 40 cars built and probably over 100 solder splices per car.....if soldering was an issue, I would have thought I would have heard about it by now? Yes, for a full-blown race car that's going to get thrashed about on a daily or weekend basis over and over....yes, I would probably change my tune....but for a street car where I have the wiring pretty well motionless and zip-tied/anchored to the chassis at regular intervals, I just can't see what is going to make it fail?

As Crash and Shoeless have mentioned, alot of this is probably going to be based on how much $$$ you want to throw at this vs the potential ROI. If I was putting $15k into the wiring supplies in every GTM I've built thru the years.....I'm guessing I'd probably be out of business right now? How long do you plan on owning this car? That's another thing to consider. If you're prone to trading cars on a regular basis.....you're probably not going to "wear out" the $200 Painless harness.....and I doubt you're going to find a buyer willing to pay an extra $15k because you invested that much in wires.

Just stuff to think about.

[crash]

You know why this place is great..."You want the nylon stuff with the gray stripe on it....high temp and won't melt under normal conditions...if you decide to use any of that."

I did not know about nylon split loom. I knew about fire resistant split loom, but the nylon stuff actually has a higher temp rating as far as I am seeing.

Learn something new every day!

Thanks Shane!

I agree on the solder joints. Never thought I would ever have any issues and never have had issues. I wouldn't use them all over the place as the go to way of connecting wires, but for a splice here and there, and done properly...no issues.

One would never see it on an aircraft, and aircraft standards are nice to aspire to, but we don't deal with any high frequency vibrations like vehicles with jet engines do...or very long wing structures that are constantly flexing and moving.

[ohmygosuness]

Crash - yes, slight sarcasm on loving to redo stuff. But I was going to redo my wiring anyway because they seem way too long and the plastic tube are just too bulky (also low melting temp, according to Shane). So, I know I was going to learn something here and eventually tear the harness out and do it right. I just wished I posted on here sooner.

Currently, I'm not planning on using the GTM for track day all the time. But I'm open to wire it well enough so, when I do want to track it more and more, I won't have the constant fear in the back of my mind about electrical issues :D

Shane - Thanks for letting me know about the nylon stuff. I'm also planning on never selling this car. Maybe I'll pass it down to my children, who knows LOL. So, now that I know the car starts without a problem (so far), I'm going to redo the wiring to make it less of a fire hazard.

[ohmygosuness]

And for the thing with soldering/crimping, I was reading this article - https://marinehowto.com/marine-wire-termination/

This might be a bit extreme because it's for marine applications. But it wouldn't hurt, right?

[Shoeless]

I was reading post#107 in your wiring thread and a couple more posts below that and the topic of crimping vs soldering came up (starting at post#112). It got me into an hour long rabbit hole researching on that topic. To make long story short, I'm going to start crimping as much as I can. I already modified the current harness through (mostly) soldering. I believe I will cut them all out and replace with either marine-grade butt connectors or open barrel crimp with shrink tube.

Also, did I mention I like the epoxy resin you used for sensors/buttons? I'll probably do that too. I'm wondering what type of consistency it has when dried. Is it stiff like clay? or rubbery?

Edit: I will also plan out the wire route with a rope or something (similar to what you did). Except, I think I don't have enough aluminum panels on yet to know exactly where I can route my wires. My next step could possibly be clico-ing up some panels to see where I can route them.

Solder vs. Crimping.

It's a hot topic in the automotive wiring world, especially once you start to look at building a hardness to the highest motorsports standards. So I'll give feedback on my approach and then I'll give feedback on what I think is appropriate for your effort. I'd like to answer it this way because crash is totally correct when it comes to cost of doing this. The tooling alone just to build what I did was close to $4-5K (I legit bought 1 tool for $600 + the $86 positioner just to be able to crimp about 30 closed barrel pins in one plug for my MoTeC C127 Dash. I used it for 15 minutes and that was it, but I can guarantee you they are 100% perfect crimps on closed barrel proprietary pins), materials cost is estimated at $5-6K, and there is no way to estimate my labor. It wouldn't be fair as I was learning as I was going so it took way longer. If I had to throw a number at this if I paid someone - probably $15K. They would have the tools, but kill me on the labor to plan an harness like mine. The amount of documentation and planning before I even cut the first wire was months (although I didn't work on it every day obviously, but you get the point).

From my training and if I was to build another harness just like mine, there are only 2 times soldering is acceptable. First, creating pig tails for sensors and actuators (explanation below how this is addressed) and second, soldier sleeves for attaching a wire to the braided sheathing on twisted braided cable (start looking at post 67-68 on the wiring post) and you will see how this is supported/secured behind very rigid Raychem shrink molded boots (and glued closed with RT125). So technically speaking there are soldier joints in my engine and chassis harness, but only in these two scenarios and you can see how they are protected even further against vibrations and possible failure.

For your application and 99% of everyone here, I'd recommend the proper crimp tool over soldier any day of the week, and you can certainly do this on a budget. But Shane and crash are correct in what they are saying. Most GTM drivers will never push their car to the limits, and this doesn't matter as much, but for me, I had different goals of learning and building something nobody else has (I'm also NOT selling my GTM ANY TIME SOON!!). For joining wires, an open barrel splice with proper crimp tool and glue lined heat shrink (Raychem SCL) over top of it, is an amazingly reliable connection. This can be achieved relatively inexpensively too. For example, here is a fantastic set of crimping tools (https://racespeconline.com/products/sargent-economy-crimper?_pos=10&_sid=194744d4e&_ss=r) that are considered "entry" level, but will elevate the quality of your splices and connections as well as creating OEM type style crimps on OEM pins and plugs (For example, I legit own these 2 tools and sent them to Shane to use on my build. They were used to crimp the pins on the OEM wiper motor plug so that Shane didn't have to create an ugly pig tail with an extra set of butt joints connecting the pig tail to the main harness simply because we didn't have something to recreate the OEM crimps. Instead, I now have as close to an OEM connection as possible for my wiper motor plug and its clean). These tools not only do open barrel splices, but they also do pins for connectors.

Interesting you found a marine wiring site that had all that info in one place, pretty decent, I perused it as I have a boat too that I work on and it's a totally different beast. Glue lined butt splices with special tools to not break the heat shrink on the terminal are used. I personally think these are great little products. Not only when they are crimped properly, then you shrink the glue lined heat shrink around it, it creates a perfectly sealed connection. There are Raychem versions of this type of application but requires a $315 tool (https://racespeconline.com/products/dmc-gmt232-crimp-tool?_pos=9&_sid=194744d4e&_ss=r). This would essentially be the step up from an open barrel crimping tool to the proper closed barrel crimping tool. Closed barrel is considered superior to open barrel and is more motorsports applicable, but wanted to share what it could look like if you tried to go up one step in build quality. It gets expensive VERY QUICKLY.

So now what if you go down in build quality? Let's talk those cheap heat shrink butt connectors that have soldier and glue all it one that you see on Amazon and FaceBook. Run, fast and hard away from these types of garbage. This kind of crap legit would make me loose sleep if they were in my car. Do they work "just fine" for some, ehhhhh maybe, but I'll pass.

I'll add to your reading list. Forget the marine page and go here. https://www.rbracing-rsr.com/wiring_ecu.html

Just take into consideration on his goals before you take all his guidance as gospel. If you read anything and you have a question, just let me know and I'll give you a sanity check on the level of harness you want to build.

The resin you are referencing is called ResinTech RT125. It comes is a 2 part tube and you need the dispensing gun, which is cheap too. It dries rock hard and completely eliminates the impact of the vibration on the solder work that is done when you are creating pig tails to put more robust connectors on sensors and actuators. What I did with the steering wheel buttons is kind of cool for the fact you can see I actually soldiered the wire to the button pins, put in strain relief (loops), and then epoxied in place. These are the same steps I followed to create pig tails for every item on my engine to use Deutsch AS Connectors as the more reliable connection.

[ohmygosuness]

Shoeless,
I just read through 30% of that article and I think I'm going to do most of what it suggested. I'm willing to throw a couple thousand dollars more into improving my electricals. That article seems to have everything I need. I really appreciate it.

What I'll probably do is divide the car into sections and, instead of running long wires from front to back, I'll make a mil-spec plug for each section. I think someone else on here also does something similar (maybe Crash?).

[Shoeless]

Shoeless,
I just read through 30% of that article and I think I'm going to do most of what it suggested. I'm willing to throw a couple thousand dollars more into improving my electricals. That article seems to have everything I need. I really appreciate it.

What I'll probably do is divide the car into sections and, instead of running long wires from front to back, I'll make a mil-spec plug for each section. I think someone else on here also does something similar (maybe Crash?).

Absolutely!!! This is a good one in the community of higher end applications. There is a ton of great info on this page and it's all done properly. If you throw a couple thousand dollars at this, you would be amazed at what you could achieve. Especially if you pay attention to used tools on ebay (they come up all the damn time, hell my DMC AF-8 that i use for all my marine applications was used off ebay). Same thing with connectors like crash has shared. If you have some time and don't mind researching, you can save a lot.

What you mention here is creating sub-harnesses. Sub-harnesses are great, if you can justify the cost of two typically higher density plugs, boots and tools to build it properly for each section you are interested in isolating. In my GTM I have an Engine Harness and a Chassis Harness build to mil-spec standards. I have no sub-harnesses. Could I have added a couple, sure, but I don't have any need for them in how my GTM is set up. Think it out logically and if you can justify it and it makes perfect sense to you, go for it!!

[VRaptor SpeedWorks, LLC]

.....and keep in mind that every connector you add into the equation adds 3 new potential failure points for each circuit......wire to pin crimp on one side, pin to pin connection inside the connector (as well as pins staying seated in the connector) and the pin to wire crimp on the other side of the connector.

[ohmygosuness]

I'll definitely have an engine harness and a chassis harness.
I'm thinking about doing some science experiment while building this car but it would increase the amount of wiring needed in the engine bay. There's definitely a lot more planning to do for wiring while I still have the AC/dash/lights to figure out.

Do you guys use an "enclosure" for your ECU? I'm thinking about getting a box like picture below. Drill out some holes and put some grommets for the harness.

217712

[crash]

.....and keep in mind that every connector you add into the equation adds 3 new potential failure points for each circuit......wire to pin crimp on one side, pin to pin connection inside the connector (as well as pins staying seated in the connector) and the pin to wire crimp on the other side of the connector.

This.

Keep the bulk head/sub harness connections to a minimum. If you want to spend some more money then look into doing Power Distribution Units. This simplifies the wiring by using CAN bus technology, but drives the expense up considerably. Again, as we have discussed before, this puts more electronics into the wiring equation which are great until they are not.

I have added some electronics, like an automatic fuel tank switcher so that our fuel load remains equal between sides of the car during a full load fuel burn, but have a phisical switch that takes the electronis out of the loop if needed. Again, electronics are great...until they aren't.

[crash]

I'll definitely have an engine harness and a chassis harness.
I'm thinking about doing some science experiment while building this car but it would increase the amount of wiring needed in the engine bay. There's definitely a lot more planning to do for wiring while I still have the AC/dash/lights to figure out.

Do you guys use an "enclosure" for your ECU? I'm thinking about getting a box like picture below. Drill out some holes and put some grommets for the harness.

217712

I would not recommend enclosing the ECU. Again, not entirely familiar with the Haltech ECU, but every ECU I have dealt with previously requires air flow over the ECU body to cool the electronics within. If the ECU is not water tight to begin with, then you need to find a different ECU.

[ohmygosuness]

I would not recommend enclosing the ECU. Again, not entirely familiar with the Haltech ECU, but every ECU I have dealt with previously requires air flow over the ECU body to cool the electronics within. If the ECU is not water tight to begin with, then you need to find a different ECU.

I think Haltech did mention it's water-tight. Currently, the ECU will be placed close to one of the side vents where it may expose to dirt and rain. My concern is keeping the ECU clean. I could use this box without the lid or mount a tiny computer fan on it, but again, more electronic failures :D

[Shoeless]

I think Haltech did mention it's water-tight. Currently, the ECU will be placed close to one of the side vents where it may expose to dirt and rain. My concern is keeping the ECU clean. I could use this box without the lid or mount a tiny computer fan on it, but again, more electronic failures :D

You will be fine and not need that box for the reasons crashed mentioned, plus, anything that just makes the volume of something larger in the GTM than it needs to be is no good due to available space.

On the sub-harness points, I totally agree. Keep them to a minimum, but if you have the justification and means, go for it. Just knowing you are adding additional possible failure steps.

Funny timing on your mention of adding things in the engine compartment. I need to change the configuration of my air intake to get a larger filter in there. I'm going to try and do some experiments on airflow in the engine bay for best placement once I revise this. I'll video document the whole thing of course :cool:

[ohmygosuness]

You will be fine and not need that box for the reasons crashed mentioned, plus, anything that just makes the volume of something larger in the GTM than it needs to be is no good due to available space.

On the sub-harness points, I totally agree. Keep them to a minimum, but if you have the justification and means, go for it. Just knowing you are adding additional possible failure steps.

Funny timing on your mention of adding things in the engine compartment. I need to change the configuration of my air intake to get a larger filter in there. I'm going to try and do some experiments on airflow in the engine bay for best placement once I revise this. I'll video document the whole thing of course :cool:
That's what I was thinking! (With air flow in engine bay). I'm thinking about setting up some thermocouples in different areas as well since I'm planning to add a couple fans in the engine bay to direct air flow.

On a different topic, I'm also thinking about building an automatic adjusting spoiler (because supercar :D). But that's after I got everything else sorted out.

[crash]

We used to mount the GM ECU in the engine compartment. This was to keep the wiring as short as possible and to make engine changes easier because the ECU came with the engine when it was removed. We ran a separate flexible air duct up to the ECU from the side vent to try and keep it cool.

Take a look at many of the OEMs and you will see the ECUs mounted in the engine compartments. Heat is the only issue here, but it keeps the ECU essentially with the engine and the wire runs short and uninterrupted. Most street driven cars really do not have issues with heat. Exposure to the elements happens and is simply not an issue with the way ECUs are built.

With the increased cost of non OEM ECUs I have moved the ECU into the driver's compartment. This keeps the ECU cooler and safer in the event of an engine fire.