Wiring harness

[flynntuna]

How much of the wiring harness has to be used for the engine to run properly? Beside of the computer, engine harness,and gauges. For the rest, headlights, taillights, brakelights, turn signals, wipers, and for some, a/c heat ect. wouldn't it be easier to start from scratch, especialy since the condition of the harness is an unknown?

[timmy318]

When I was at FFR, I saw the 818 chassis in early June and he wiring harness was a mess. I talked with Dave and them and they said that soon they would tackle the challenge and trim it up a little bit. Using the original harness is completely optional in my opinion. My dad is an electrical engineer and he created a wiring harness just for our HR!

[PhyrraM]

If you can affordably 3rd party source all the proper ECU, sensor and actuator connectors and pins then fabricating a harness becomes feasable. Until then you will still need a donor harness to physically plug into all the components it take for the motor to run.

[metalmaker12]

If you can affordably 3rd party source all the proper ECU, sensor and actuator connectors and pins then fabricating a harness becomes feasable. Until then you will still need a donor harness to physically plug into all the components it take for the motor to run.

Agreed, it is just a lot easier and cheaper to use the Subaru harness, it is not that complicated and is proven to work, why would anyone want to not use it and follow FFR guidance is beyond my comprehension.

[Xusia]

^what he said.

I've got decent electrical knowledge, and I'd bet it's far easier to remove the factory harness from the donor and trim it down the factory harness (to just what is needed) than it is to build a custom harness. The factory harness is highly reliable and will ensure compatibility with options or add-ons designed for the Impreza platform. One COULD make their own harness, but I really don't see the advantage.

[longislandwrx]

I'm sure as in the past, the instructions provided by FFR to trim down the harness will be top notch. I imagine it will still require the use of the factory fuse panel (both engine and cabin) but unnecessary circuits will be eliminated.

however the 818 may take the route that the GTM uses which is a painless wiring universal kit for the std stuff lights/turn signals etc and a modified factory harness to run the motor.

[skullandbones]

Not to get argumentative (haven't check recent build manuals) but FFR didn't give instructions on how to "diet" the harness except to hook it up, make sure all the essentials worked, and then start removing one circuit at a time checking back that everything still worked (actually pretty good instructions). I think that would be a separte instruction manual to itself.

I agree that a better course would be to go with a new basic body harness and then "diet" the engine harness as needed. On my roadster project that was my plan but when I got into the engine harness, it just didn't look that good (some wires fused together due to age, and generally rough looking condition and feel of the wires). So I got an aftermarket EFI harness as well. That was the best move I have made on the build. I don't know if 818 builders would even have that option. But going with a simplified wiring system is definitely an "anxs" reducer and easier to route during the wiring process. Even with the simplified system, I still have a lot of circuits I have to shorten and deadend but nothing like a factory harness. Thanks, WEK.

[PhyrraM]

.....however the 818 may take the route that the GTM uses which is a painless wiring universal kit for the std stuff lights/turn signals etc and a modified factory harness to run the motor.


Possibly, but I would guess that the $9900 price point is the biggest indicator of what FFR will go with for the basic kits.

[longislandwrx]

although a basic kit, something like

http://www.ebay.com/itm/10-Circuit-Wire-Harness-street-hot-rat-rod-wiring-12v-Keep-Clean-PROCOMP8B-/330626251511

would give you signals, column power, horn, brakes etc for under $100.

[flynntuna]

I'm going to have to rely on the vast knowledge of the combined forum, my hope is for some detailed posts to ge me thru this complicated part of the build.

[PhyrraM]

I'm going to have to rely on the vast knowledge of the combined forum, my hope is for some detailed posts to ge me thru this complicated part of the build.

That's the thing...The factory harness obviously has everything you will need to complete the car. Lights, engine, gauges, even ABS for the adventureous. The problem is that there are changes in the harnesses through the years and model lines - even trim levels. This will make a single, comprehensive set of instructions very difficult to write. And the logistics of 'custom' instructions for each variation of the harness make such an endeavor very hard.

Over time, as more builds get done, I expect the common combinations to be documented. But generally, most folks tend to get so wrapped up in work when it comes time for wiring that the documentation side of it gets sloppy. You can see it in numerous Subaru build threads, on various Forums. You can be following a build with many posts and pictures of each step - then when it's time for wiring the updates stop. Photos don't get taken or posted. A few weeks later you get a "THE WIRING IS DONE" post with an apology about the lack of pictures and details. I think that 818 build logs will be the same. Wiring takes a bit of concentration and research, leaving less time for documentation.

Wiring is going to be one area where the builders are just going to have to roll thier sleeves up, do some reading, and get dirty. Even if you use a 'hot rod' type of harness for the bulk of the car, you still have to do the engine control. At this point Subaru does not sell a harness kit like Ford or GM do. Maybe a 3rd party can fill this gap if the kit becomes popular.

I plan on doing a lot of documentation, and will make extra effort on wiring. However, current finances mean that I most likely won't be in the intial round of builds. Likely a year or so down the road. I am accepting donations though.:p I have also toyed with the idea of selling modified harnesses or a harness 'thinning' service because wiring has never really scared me (bodywork terrifies me though).

[Olli]

A few years ago I built a rear engined Subaru powered car. It was a 2.5l Sti turbo. I did not use the Subaru ECU and its' associated wiring. The ECU was a MicroTech. Here is a picture of the complete engine harness including the ECU and the seperate ignition box. You can also see relays for the fuel pump and cooling fan. I'm just posting this as an alternate suggestion.

Olli

http://i34.photobucket.com/albums/d101/ollijo/Photo2-5.jpg

[wallace18]

Nice neat install.

[RM1SepEx]

It appears that there could be a very nice niche here for an enterprising individual... NOT ME! I'm a mechanical junkie and don't "enjoy"the wiring aspects.

It could be worse, my 69 Sonett has Lucas wiring, they don't call him the prince of darkness for nothing... 1600 lbs unique... check out the body and frame. With my engine mods it should have about 80 WHP (63-4 stock ENGINE HP) 1500 cc Ford V4

1176011761

[longislandwrx]

that microtech is a nice setup. Had the old school version on my old RX7... for about 1200 its a pretty sweet deal.

[Mifune]

So no harness comes with the FFR 818 kit?

[flynntuna]

The wiring harness comes from your donor. It needs to be modified to fit, which makes it for me the hardest part of the build. I expect the wiring to be more than 50 percent of the time I spend on the build. Hopefully I'm overstating. We'll see LOL.

[metalmaker12]

Microtech is a good option, but I am in the process of dieting my Oem harness pretty neatly, so I am going to be happy with my setup. Plus a penny saved is a penny for other things.

[Bill Waters]

I wonder if anyone has any insight at this point as to the best options for a wiring harness for the R? I'm sure the arguments made in this thread for use of the donor harness in the S are sound, but I would think the R would require a much less elaborate approach.

[Jeff Kleiner]

I believe Wayne has a harness and engine management system in the works.

Jeff

[fateo66]

If anyone needs factory wiring diagrams, PM me with your email and desired year and I'll send you a pdf.

[mobius]

I believe Wayne has a harness and engine management system in the works.

Jeff

What engine mgt system? I have been looking at the Haltech system...

[Wayne Presley]

What engine mgt system? I have been looking at the Haltech system...

I'm doing Electromotive and MegaSquirt now.

[metros]

Plug and play harness???

Add that to my build budget. K Thanx.

[bstuke]

I'm doing Electromotive and MegaSquirt now.Would the MS be better because it uses the stock crank trigger? I also went to Pullapart yesterday and picked up a cable based TB and all the tidbits including a gas pedal.

[Frank818]

Would the MS be better because it uses the stock crank trigger? I also went to Pullapart yesterday and picked up a cable based TB and a all the tidbits including a gas pedal.

That doesn't mean much. "Being better" implies a lot more than the "plug and playing" of the crank trigger. For instance DTA also uses OEM crank sensor, does that mean it's better? No it depends what you do with the car, what you want to control and how you want to control. All in all though it's true it's usually easier to use all OEM sensors, but there exist very simple stand alones that don't use OEM trigger (SDS is one). Simple sometimes means "limitations" too, so beware. Make sure the usage you'll do with the car is well supported by the stand alone (for instance SDS is awfully bad with idle valves, so as a daily driver it's not that good, but if you want the minimum of possible headaches when it comes to fuel and timing tuning, SDS is great, but limited again :)).

[bstuke]

My thought on the crank trigger was reliable, repeatable.

[alpine227]

I'm doing Electromotive and MegaSquirt now.

Do you have experience with ms on the Subaru ignition setup? From what I gather the zeal daughter board should allow for use of the factory crank and can sensors to facilitate coil on plug and sequential injection. Or are you planing to use a missing tooth wheel with wasted spark?. I am looking at using ms as its what I know with a Linux bare bones PC feeding a touchscreen display for a gauge cluster. Just need to work out a fuel level gauge.

[indiana818]

nice, clean setup i will investigate this option
kerry

[indiana818]

just pulled the harnesses off my 2002 subaru impreza today. what a mess i would appreciate diagrams if you have them for this car e-mail rimexlighting@yahoo.com kerry sylvester

[Xusia]

PM Fate66 requesting a 2002 wiring diagram. Provide your email address. :)

[Mechie3]

I email him last night with this link:

http://ken-gilbert.com/impreza-manuals

has the 02-03 wiring diagrams on there.

[indiana818]

I al looking for a2002 n/a 2.5. Diagram
Indiana818
Kerry
Thanks in advance

[GUNS]

Does anyone know if a painless kit would work? Seems like it would be easier to use that than teardown the entire OEM harness. Thoughts?

http://www.summitracing.com/parts/prf-10202/overview/

[longislandwrx]

Yeah it's an option, just use the engine and fuel harness, and then adapt your column with the painless kit. Keep that obd2.


the only time consuming part would probably be splicing the column connector in, but probably just a few hours.

[FFRSpec72]

So there are no instructions on how to diet the harness?

[Xusia]

Mechie3 made a thread dedicated to dieting the harness.

[Mechie3]

So there are no instructions on how to diet the harness?

I think the instructions say something like "plug it in, make sure it runs, then cut stuff out". Lol.