I understand the IPC communicates to the serial data buss like the PCM, BCM, etc. does.

However GM does not refer to it as a module like in PCM, BCM, etc.
They refer to it as just IPC. I thought maybe it was to keep it at 3 letters but the have a left door control module LDCM.

My question is, if I drop the lower cluster valance will I see something that looks like a module????

I'm trying to look into a cruise control problem is why I ask.

 

Hi Larry

I don't think the IPC (Instrument Panel Cluster) is any kind of "module" at all - I think IPC simply refers to the unit that contains the tach, speedo, other instrument indicators, lights, and DIC. I'm not sure, but I don't think there are any chips in there that control anything. I think everything in the IPC is controlled by other modules. I think it only "receives" communications from the other control modules.

The Service Manual says:

It goes on to say that the ECM/PCM and BCM communicate with each other over the GMLAN serial data circuit to do what the switches tell them to do.

I see ablsolute nothing that says there is anything in the IPC that gets involved in the communication between the switch, the PCM, or the BCM, and there is no "Cruise Control Module".

The diagnostic section says:

I reviewed the diagnostic checklist and didn't see anything about checking systems and operating the brake/brake lamps. The only reference to the brake lamps was in that statement above that leads into the test/diagnostic checklist procedures. One checklist item tells you to check the resistance load between the cruise control switch and the ignition voltage circuit. Maybe a problem with the brake lights would create a resistance/load that the cruise control wouldn't like.

So.....one thing to check might be your brake lamps. I know you have a trailer, so perhaps there's an excess resistance in them that's creating a problem.

Good luck!!!

Bob

 

Hi Bob, and thank you for the reply.

***Let me give you a few symptons of my cruise contol.

A. It will kick off for no reason

B. Many times you will get a slight acceleration just before it kicks off.

C. A couple of times the speedometer has dropped from 70 mph to zero for a second and back to 70.


I feel like it is losing the speed signal but the speedometer has only dropped a few times and the cruise has kicked off hundreds of times.

If you get bored look at a code U1000. It indicates that the IPC communicates with the serial data buss but it stops short of calling it a module.

Also maybe look at a U1096.

Did we ever determine what is the least costly reader that will read BCM codes???

PS I just found a reference to a DLC, data link connector, on the LH side of the instrument panel behind the steering wheel.