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I am very confused with the wiring on my 1985 c4, the research I have done is that the ecm/pcm for a 85 is #1226870, and for the 86-89 is #1227165, anyways on the 85 ecm/pcm the pin c10 on the larger connector is a ground for the CTS and IAT and the MAF has its own dedicated ground, but on the 86+ model pin c10 it’s a yellow 5v reference wire to the CTS, and on my 85 C4 pin c10 is a yellow 5v reference wire, do I have the wrong wire harness? I bought the car a couple months ago and don’t know the full history what the previous owners did to it, is the ecm/pcm pin layout I uploaded used for my 85 harness and ecm??
Last edited by Nolandoan; Feb 12, 2026 at 06:09 AM.
Yea that’s what it seems like to me tomorrow I’m going to check the ecm number and go from there, do you have any wire schismatics that are solid and not for a Camaro 350 I don’t think I have reliable schismatics, thank you.
1985 C4 wire issues
