Project86- My first (and probably not the last) Rebuild

[TitaniumTT]

I woke up and my ears were burning

I'm not familiar with the RacePak unit. I can tell you that my AIM digital dash uses CAN communications with my Motec so I didn't have to double up on sensors. I'm afraid that with my FD, I'm going to need to double up on a few, if not all of them becuase I don't think that I'll be useing the same dash. Like Sean said, it works in the FC dash becuase of the inherent recess, I think it'll look like crap in the FD. So basically everything that I want gauges for, I'll need to double up on. Coolant, Boost, FPSI, OPSI, Otemp etc etc will need two sending units, one for the Motec, and one for the gauge - that really pisses me off actually. I need to do more research and see if I can avoid that.

As for the wiring, here's what you need to do - you need to match ALL the harnesses. For example - you can't use an S4 chassis harness with an S5 Dash harness. As you found out, little things are different. Different enough that it's just not worth the headache of trying to make everything work together. Inevitably, I believe something will get mixed up and the little electrical Genie will pop up and fuck stuff up. As you've already witnessed. If there was a burning smell, there was probably a puff of smoke somewhere and the genie is out.

So, If you have an S4 car, you already have the S4 chassis front and rear chassis harnesses. All you need now is an S4 dash harness, engine harness, and all the S4 switches etc etc and it'll work just fine.

I stripped a TON of wiring out of my harness for things that I either wasn't using, or wired up myself. My car was originally an SE. I didn't have PW, PDL, PM, I stripped out my A/C and a few other things. Basically it's alot of staring at wiring diagrams and tracing the wires inside of the harness. You'll find a metric shitton of wire splits. The b/y is a very common one to split all over the place as is the b. the Bl/W is another one that runs all over the place as well. Here is where planning is a BIG thing. Say for example you're installing a rear hatch solenoid that requires about 10A and you're not using any of the factory stereo amps. Well there is a (I BELIEVE) a Bl/W wire that goes all the way from the fuse box all around the car to power the Amps. Although this is only active when the key is on, so it won't work when the key is off. It may be nice to use that as the ign hot to the trigger of a fuel pump relay though.

It's shit like that that needs to be taken into consideration. It's a long, monotonous arduous task that requires alot of patience and planning to get it right, but in the end, it's worth it. I pulled a few BOXES of wires out of my harness. Most, as in 80% if not more of the wires going across the tranny tunnel to the ECU I stripped out becuase I have my own coil & trigger wires in my engine harness - all of those could go. All of the trigger and power wires for the A/C went with the excpetion of one or two power and trigger wires.

I think the best way to attack the problem from a starting point is to do exactely what we did with Alex's car. Make a list. This list needs two columns. One side is things to add, the other is things to subtract. The things to add side needs lists of wires that need to be added. See if anything from the list to be subtracted side can power the list to be added side. If so, cross those off the list to be subtracted side. Then start tracing wires and pulling them out of the harness. DO NOT CUT ANYTHING though. What you'll find is that whire you can trace one color of wire from the harness of the load all the way back to the fuse box or control control box, it may be a wire that is used for something else. In this case, it will not appear in the FSM wiring on the page that you are looking at becuase that other circuit may be in a different location. Instead what the factory does is split the wire somewhere in the harness. If you strip this wire out at the source, you'll kill both circuits and one may be a circuit that you don't want to take out. The stereo and the rear defrost I think is a good example, as is the infamous B/Y wire that is just EVERYWHERE. You need to start at, say the speakers, and work you're way towards the fuse box/dash harness. If the wire splits, open up the wrap and cut it, then re-wrap it and leave it there. If that wire appears again on you're subtract list, you'll find it again at the source of the load and be able to work back again.

Better to take your time and do it once than fuck it all up and be looking for a replacement harness.

Something else to consider - and this is something that I'm doing over the winter in an effort to simplify my incredible complicated simplified electrical system Yeah I know.... what I did was installed a battery cut-off switch. The issue with that is that you need to wire in a few constant hot circuits to do things such as keep your radio memory, alarm, PW, PDL, headlights, interior lights, etc etc etc. The things that need to be on even when the battery is shut off. I added an external fuse box and relay box. What I ended up doing is running larger gauge wires all over the place. Over the winter I'm going to get my hands on Alex's spare S4 harness (becuase even though his car is an S4, we're using all S5 harnesses because he wanted the S5 interior) and strip out a bunch of wires that I need to be constantly hot. Things mentioned above that have factory circuits. Break them from the main supply in the fuse box, and route them to a powerpost (or something similar) connected to the battery. Greatly simplifing my mess located where the factory ECU once was.