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Discussion Starter · #1 ·
Hey guys. I’ve been tracing a short for what seems like a lifetime lol. I have it isolated to a single wire coming from the pcm. The short is in the wire, not the pcm. I’m looking at the wiring diagram but I’m having trouble figuring out which of the 3 connectors on the pcm are c1,c2, etc. being very color blind is a great asset to this lol.
I’m looking for this wire marked in the picture. The Lt Blue/Dk grn wire on pin 14 of connector 3. Looking at the pcm picture, which connector is c3 and how do I locate pin 14? Thanks a ton!
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Discussion Starter · #3 ·
Ok so, I found the wire in the c1 connector at the firewall. The short is somewhere between that connector and the pcm connector. That harness looks like it goes into a valley or something in the engine. Instead of trying to take all of that out, I cut the wire at the c1 connector and ran a new wire to the pcm plug. The short is gone, but the esp bas and traction control lights are on. No codes are being thrown though. Are they related in any way to the lt blue/ dk grn wire from the brake switch?
 

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Ok so, I found the wire in the c1 connector at the firewall. The short is somewhere between that connector and the pcm connector. That harness looks like it goes into a valley or something in the engine. Instead of trying to take all of that out, I cut the wire at the c1 connector and ran a new wire to the pcm plug. The short is gone, but the esp bas and traction control lights are on. No codes are being thrown though. Are they related in any way to the lt blue/ dk grn wire from the brake switch?
Pretty sure ESP and traction control are dependent on the brake signals, since they are just an EBS--so very likely related.
 

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check the 3 circuits on the brake switch are working correctly,
if there was a short on that wire then fuse M15 would have blown, if that wire was somehow broken then that would explain a few things,
the fact that you can select gears with the shifter when the brake switch connector is unplugged is very strange, normally thats impossible, when you press on the brake pedal the brake switch sends 3 signals:
1st brake signal: goes to the TIPM, cluster, high level brake light, shifter, and the trailer hitch wiring,
2nd brake signal: is a 12v + to the ECU
3rd brake signal: is a Ground to the ECU
i see in the photo above that the red safety clip is broken off on the #3 connector on the ECU, maybe someone has been touching the wiring previously,
 

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Discussion Starter · #7 ·
I replaced the brake switch first. I actually got it fixed today. The problem was definitely the LtBlue/DkGrn wire that runs from the brake switch to the pcm c3 connector. It has a short somewhere in the harness between the pcm and the main c1 connector at the firewall. The harness snakes though the engine so instead of tearing that apart, I cut that wire at the c1 and ran a new wire across the firewall to the pcm connector. Only problem is that I grabbed the wrong wire the first time and it triggered the eps bas traction control light. once I realized that I had the wrong wire (LTBlue/Red), I put that one back and got the right wire. Now it’s running perfect, no lights, no issues. Thanks a million for your help!
 
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