Gen 4 Coyote Wiring Questions

I still don't have my engine in the shop but continue to plan out the wiring connections while I wait. Most of what I'm seeing is very straight forward and I've created a document for what I have planned:

https://thefactoryfiveforum.com/atta...8&d=1776698968

I have two questions that I am still unclear on. Anyone that has installed a Gen 4 Coyote have any details on the following that they can share:

1. Fan wiring? I see a control wire in the Coyote harness that I assume I can run directly to the fan or to the RF relay to allow the Coyote PCM to control the fan. My question is whether there is a preferred method and a secondary question is what to do with the A/C fan wire in the FFR A/C wiring harness? I see that one of the RF Fan Thermo Control wires goes to the trinary switch, so that leads me to believe I should be controlling the fan through the RF fan relay. What is the purpose of the fan wire in the A/C harness where the power and ground wires are?

2. The MIL for the Gen 4 looks like a light that is provided alongside the OBDII connector. There is no ground wire in the IP pigtail for the MIL like I see in some on-line references. Can anyone explain the MIL setup with the Gen 4 control pack that FFR ships with the engine? I'm looking for a MIL (-) wire that I can connect to my Dakota Digital gauges to light the check engine lamp in the gauge when the Coyote signals the MIL.

Thanks,
Dave

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Originally Posted by Papa

I still don't have my engine in the shop but continue to plan out the wiring connections while I wait. Most of what I'm seeing is very straight forward and I've created a document for what I have planned:

https://thefactoryfiveforum.com/atta...8&d=1776698968

I have two questions that I am still unclear on. Anyone that has installed a Gen 4 Coyote have any details on the following that they can share:

1. Fan wiring? I see a control wire in the Coyote harness that I assume I can run directly to the fan or to the RF relay to allow the Coyote PCM to control the fan. My question is whether there is a preferred method and a secondary question is what to do with the A/C fan wire in the FFR A/C wiring harness? I see that one of the RF Fan Thermo Control wires goes to the trinary switch, so that leads me to believe I should be controlling the fan through the RF fan relay. What is the purpose of the fan wire in the A/C harness where the power and ground wires are?

2. The MIL for the Gen 4 looks like a light that is provided alongside the OBDII connector. There is no ground wire in the IP pigtail for the MIL like I see in some on-line references. Can anyone explain the MIL setup with the Gen 4 control pack that FFR ships with the engine? I'm looking for a MIL (-) wire that I can connect to my Dakota Digital gauges to light the check engine lamp in the gauge when the Coyote signals the MIL.

Thanks,
Dave

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I am using the Coyote fan circuit to operate my fan and PWM unit. You can use the RF fan circuit for something else or you can choose to let it lie. I believe the other circuit you are referring to initiates fan power when the AC compressor is activated. I believe Paul covered this in an old post. When he queried F5 they stated the duplication of the circuit doesn't matter and will function as is.

When I look at the MIL wiring in the Control pack instructions it looks like you could tap into wire MIL01 for the Dakota Digital feed you need:
Attachment 228389

I am working under the assumption F5 is shipping a standard control pack harness which contains the MIL and OBD connections. You could also reach out to Ford Performance to confirm this wire would work for your needs.

I think Tim covered it. But here are my responses FWIW. From two Gen2 and one Gen3 installations. But neither of what you're asking about changed between those two and I've heard the Gen4 control pack is basically the same as the Gen3.

I've always had the Coyote control pack control the cooling fan directly. The control pack wire to the fan motor plus ground and it's done. That leaves the RF fan circuit out of the picture and it's available for something else or just not used. With A/C the picture changes. Still the Coyote control pack wire to the cooling fan. But also the RF cooling fan circuit is in play via the trinary switch as Tim mentioned. So both power leads go to the fan. The fan can be triggered either by the Coyote PCM using power from the Coyote PDB. Or by the trinary switch and powered by the RF circuit. As Tim mentioned, I asked FF about this back in the day and they said it was correct and OK. Two A/C installations done this way and all OK.

I haven't dug into the pin-outs for the MIL like Tim showed. But what I can say, if it matters, is that the PCM lights the MIL by closing the ground. Took some digging with Ford on my first Coyote build to confirm this. They had it wrong in their initial instructions. On previous builds, I removed the indicator by the ODB2 port and put my own on the dash. On my Mk5 build, I'm taking the path of least resistance and leaving the MIL on the ODB2 port. It will be in my sight lines where I'm mounting it under the dash.

Thank you both for the responses. The only question I have left is what to do with the fan wire that is bundled with the A/C harness power and ground wires?

I don't see it mentioned anywhere and it isn't on the schematic in the A/C instructions.

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Originally Posted by Papa

Thank you both for the responses. The only question I have left is what to do with the fan wire that is bundled with the A/C harness power and ground wires?

I don't see it mentioned anywhere and it isn't on the schematic in the A/C instructions.

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Dave - I had to walk out and look at my harness to understand what wires I think you are referring to. My heater/A/C harness does have a separate loom marked fan, which I honestly had forgotten about. There is a ground wire with an eyelet and a dark blue and a red wire that are not terminated. And I have no idea where these go. I just reviewed the A/C schematic and there is no dark blue wire indicated anywhere that I can see. The red and black may be the two wires they show between the A/C switch and the fan switch but I don't think so. I am guessing this is the power circuit for the Evaporator fan switch but it's going to take a little more investigation since there is no dark blue wire indicated anywhere.

If these aren't the wires you are speaking of then please disregard this.

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Originally Posted by PNWTim

Dave - I had to walk out and look at my harness to understand what wires I think you are referring to. My heater/A/C harness does have a separate loom marked fan, which I honestly had forgotten about. There is a ground wire with an eyelet and a dark blue and a red wire that are not terminated. And I have no idea where these go. I just reviewed the A/C schematic and there is no dark blue wire indicated anywhere that I can see. The red and black may be the two wires they show between the A/C switch and the fan switch but I don't think so. I am guessing this is the power circuit for the Evaporator fan switch but it's going to take a little more investigation since there is no dark blue wire indicated anywhere.

If these aren't the wires you are speaking of then please disregard this.

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Tim,

Those are the wires I'm talking about. I believe the power (red) gets connected to the RF heater wire. The ground can go to chassis or any ground point. It is the blue wire I'm trying to figure out.

Dave

I dug into this and you're right - they cover these wires on pages 104 and 105 of the A/C instructions. It's a little odd this harness doesn't really show up on the schematic but the RF brown heater wire connects to the red wire and the blue wire is connected to one of the two RF green thermostat wires. Ground is just connected wherever convenient.

Thank you, Tim. I had missed that detail in the instructions. I'll need to do a full read before asking more questions.

Dave

Okay. So after reading the A/C instructions more thoroughly, I think I was getting hung up on reading the wiring diagram too literally. I knew I needed to tie the RF Fan Thermo Control to the blue wire on the trinary switch, which is shown on the diagram. The reality is that the blue wire gets connected to the RF wire at the other end of the harness where the power and ground wire are. That wire runs through the harness and connects to the trinary switch. Mystery (in my mind) solved.