Help!! Possible wiring issue??

[3seriersD]

Been working on my 85 325e for a few months now, redid a lot got everything dialed in but can’t seem to get her to start and idle. Replaced the harness with one from an 86 325e and I noticed a few differences. The first were the connections to the starter. Came with the red positive that connects to the alternator and starter, which was the same. But what was different was the 86 came with a black negative wire, not the same on the 85 harness. 85 harness came with a spade type connector that was on the bottom of the starter. After some research and wire tracing I found out that they were essentially the same just the end connection was different. Spliced it and solved that issue. Second thing I noticed was that the 85 had a square c101 and the 86 had the circle c101. Found the pin diagram easily and mated each pin into the square port. Also noticed that there is one less pin on the square end. Not sure if that is an issue. My main concern is why my ICV is not operating. Before swapping out the harness I noticed my icv was not working so I got a new one and same problem. Traced it back to the ICU module. My original module wasn’t giving out the proper voltage to the ICV. Got a new one when I got the harness. Tested the new module with the original harness and the IVC started buzzing with key on as it should. Thought I was good with the new module. Fast forward to today new harness put on and now the ICV doesn’t work again. Tested the connection to the ICV and low power output again. What could have gone wrong from just swapping out the harness??? Help!

[tomstin]

Unfortunately, I think you are going to need to basically trace one wire at a time from the sensor / connector to the ECU. The harnesses changed a lot form 85 to 86 (as you've discovered). The other thought is how are the grounds? Poor grounding will cause all kinds of issues. Sorry, but no easy answer.

[3seriersD]

Unfortunately, I think you are going to need to basically trace one wire at a time from the sensor / connector to the ECU. The harnesses changed a lot form 85 to 86 (as you've discovered). The other thought is how are the grounds? Poor grounding will cause all kinds of issues. Sorry, but no easy answer.

I did change out the grounds, one of the first things I did when I started this project. My Suspicion is that I caused a short when I did the slicing seeing as I used the 86 loom. I was left with one wire not going to the square end of the 85 c101.