Hey all,

Anyone else ever got this? It is the ICM getting more than 4.5 volts (Not sure from what but from coil I think).

I have had it happen to me 2X and both after high RPM runs.

The GM manual gives 2 solutions: change ICM or it is wiring. Seems to me that the coil could be involved.

 

If the IC line breaks, it will cause the pin at the PCM to go higher than 4.6 volts. If you have a weak connection at either of the 2 ends and get excessive vibration, it can momentarily loose it's connection. However, you should know that the PCM only checks for the voltage on that line when the engine is below 1500 RPMs. So how this has anything to do with racing is any ones guess.

I would check the line while wiggling the entire length and if you can't get it show that way, change the ICM AND the coil if they haven't been changed before.

 

Where did you get the impression that this was a coil problem. From Shoebox's LT1 DTC list:

DTC 41 - Ignition Control (IC) circuit (open circuit)

The control circuit is the white wire to the ICM, as pointed out in the response above. The diagnostic chart starts at the white wire, and only works its way to the coil voltage supply as the last step.