Chevy Trailblazer Gauges Not Working

Dash gauge Problem with my 2004 Chevy Trailblazer. ABS, seatbelt, battery, parking brake light. Installed aftermarket radio 4-5 months before problem. Rebuilt instrument panel cluster. All gauges in IPC are bottomed out except tach and speedo. ABS,seatbelt,battery, and parking brake lights constantly stay on. Cruise control works, but indicator light saying I am in cruise doesn't appear. Also, the gear indicator light telling me if I am in P,R,N,etc.. Doesn't highlight the gear I am in.

Had cluster rebuilt, problem still there.
1st question:
Could you possibly provide me with information that gives a pin out of my IPC harness and the voltages that should be there.

2nd:
ECU location and the harness that goes to my IPC pin out with voltages. I didn't make a donation because I wasn't sure if this information is available through this sight, but I will gladly make one if it is.

Answer:
After reading about the different problems with different seemingly unrelated indicators / gauges, i looked through some schematics. The thing that stands out is that then tach and speedo signal are given to the IPC from the PCM from their own, separate circuits. ALL the other indicators get their signal from the PCM, but on a different circuit. In other words, all indicators are feed from the PCM to the IPC on 1 wire, called the Class 2 serial data line. The speedo has its own wire, the tach has its own.

First be sure to check ALL fuses. Underhood fuse block, and block under the rear seat. If all ok, i would suspect either a PCM problem, or more likely a problem with the serial data wire between the PCM and the IPC. A continuity check of that circuit is probably your best / next check.

Question:
My husband just acquired a 94 Chevy Silverado C/K 1500. The instrument panel doesn't work properly at all. The odometer continues running when the truck is parked with engine running and the speedometer shows 120 while we are sitting still in the driveway. He has so far: Replaced the fuses in fuse box, tried a used replacement cluster and it did the same thing, and no effect. What could be causing this problem? Thank you for any help you can suggest :) Patricia.

Answer:
You probably have a shorted out, or faulty vehicle speed sensor. If it's sending a reading to the instrument cluster, even if the vehicle is not moving, the speedometer and odometer will keep registering miles and mph.

You can try disconnecting the sensor, which is located at the rear of the transmission if it is a two wheel drive truck or at the rear of the transfer case if it a four wheel drive truck. If you disconnect it and the problem stops, you know the sensor is bad. If the problem keeps occurring, you have a wiring problem somewhere along that harness that would need to be checked out.

Follow the wiring forward and up to the connector that is on the top area of the engine up against the firewall. We have seen a few wiring issues there.

I have a question that the results has just baffled me and others. On a 2000 Chevrolet s-10 blazer LT 4 door the dash lights would all light up and work sometimes when you started it and other times it would not. Going down the road dash lights would be working then suddenly they would go out. But when the dash lights wasn't working there was only 2 gauges that did work and they were the battery gauge & the oil pressure gauge.

When dash lights were not working on start up when you put it in gear/drive to go. It would not act right it acted as if it was in to low of a gear you would really have to give it gas to make it go. Also when all of these things going on if you ran the ac it would blow nothing but hot air. No cool air at all but when the gauges came back on everything worked as normal.

Several months later the red battery light came on as if the car wasn't running and when cut off wouldn't start back. Alternator was checked and it needed a new one put on. After new one was put on ,this is where it baffles me, EVERYTHING that I had been having problems with was fixed and hasn't happened again. Why?

Answer:
You had a voltage problem due to the bad alternator...probably not putting out enough power to run everything and that's why you had problems. Now that the system has a good electrical generator, your problems are gone.