Code po23 for a 1994 cadillac deville?

Answer 1

I have a 1995 DeVille Concours, with the 4.6 liter Northstar engine, with the same code being set intermittently for over a year now. I have both volumes of the factory service manuals. I have worked on all of my cars now for close to 50 years, and also have a very extensive background in computers and electronics for over 50 years. This problem finally manifested itself long enough for me to do some trouble shooting one day about 8 months ago and the troubleshooting tree in the book always pointed to the ICM (ignition control module), which is mounted on top of the rear valve cover on the right side of the engine, under the four ignition coils. So we replaced it once, and then a second time, since the first time did not cure the problem and actually gave somewhat different symptoms, and we thought we may have received a new one that was defective. Not sure what to do now. Don't know if you are a pro or not, but this is not something that can easily be troubleshot by the average home mechanic due to the complexity of the systems involved, the electronic test equipment required, and knowledge there of. Basically what is happening is that there is a problem between the PCM (power train control module) and the ICM (ignition control module) PO23. They interface with each other so that the PCM can control the advance and retard of the timing of the ICM. There are two modes of operation involved. One in which the PCM controls the timing of the ICM and the other in which the ICM runs on it's own with no input from the PCM and has limited capability of timing control. The normal mode is with the PCM in control of the ICM (closed loop). Hope this helps. If and when I find out more with my problem, I'll let you know. Thanks Ira.