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currently reading 1640 ohms of resistance on my ground ( yellow wire) going into my icm on my 1985 corvette does anyone know where this ground goes to or have the diagram? ive been unable to find anything this far online about this
currently reading 1640 ohms of resistance on my ground ( yellow wire) going into my icm on my 1985 corvette does anyone know where this ground goes to or have the diagram? ive been unable to find anything this far online about this
Based on the diagram Im looking at for the '88, it appears to be the coolant temperature sensor.
currently reading 1640 ohms of resistance on my ground ( yellow wire) going into my icm on my 1985 corvette does anyone know where this ground goes to or have the diagram? ive been unable to find anything this far online about this
That is the ground wire that module uses to trigger coil to spark.
The module gets its ground from being bolted to distributor.
Hi Agent, reading some of these threads is a learning experience for me. I realize i am looking at a different year than the OP, but the diagram I'm seeing says this: Seems like yellow wire is signal wire from coolant temperature sensor. Am I looking at this wrongly? Thanks for your help!
Hi Agent, reading some of these threads is a learning experience for me. I realize i am looking at a different year than the OP, but the diagram I'm seeing says this: Seems like yellow wire is signal wire from coolant temperature sensor. Am I looking at this wrongly? Thanks for your help!
Wrong yellow wire. The wire in question is not shown in that diagram. Its one of the two wires on other side of module.
could a bad icm be the reason im not getting fuel pump or injectors? im still getting spark runs on fluid, car stopped working over night
Yes, the module sends the reference pulse to ECM. That part of module could be bad without affecting its ability to trigger spark. But it does not affect the 2 seconds of pump prime.
Yes, the module sends the reference pulse to ECM. That part of module could be bad without affecting its ability to trigger spark. But it does not affect the 2 seconds of pump prime.
what would affect the pump prime the pump running and the injectors? ive already tried a new ecm and repaired the fusible link
I know the module or bad/no connection at 4 pin connector at back of dizzy can cause no reference pulse to ECM to trigger injectors, but I not aware what could cause no prime other than wiring or relay.
I know the module or bad/no connection at 4 pin connector at back of dizzy can cause no reference pulse to ECM to trigger injectors, but I not aware what could cause no prime other than wiring or relay.
the relay is good its brand new do you have a diagram of the ignition switch to the ecm? i believe there may be a fault somewhere in there but im not sure what i would test
On my 86, the ecm is turned on from 12v from ignition switch, through ecm fuse and into ecm.
You could test at the fuse to see if ignition is sending the 12v when cycled on.
Terminal A6 of ecm is ignition input.
after using chat gpt by giving as much info and diagrams i could find ive found that a6 leads to a splice off of the ignition switch which feeds many things including the esc and is the reference to prime the pump however mine does not have continuity to the switch so im going to dig into that
Last edited by n0tdads86vette; Sep 15, 2025 at 03:40 PM.
icm ground issue
