2004 Sunfire Odometer Reads Error, some Gauges dead, all lights on

Okay… I will go through the timeline here… Im usually really good at fixing these types of things but this has me stumped.

-At first, the car stereo wouldnt turn off when the car was turned off (the battery died many times :P)
-I learned my lesson, and manually turned it off every time I got out.

-Then the radio started acting weird an randomly shut off, switched modes etc.

-Then while driving one day… the “Theft” light turned on while driving and the radio shut off. The odometer read “error”. It would go back to normal, but stay for longer periods of time when it happened.

-Then the car had problems starting, AND the day lights wouldnt turn off 50% of the time (I had too unhook the battery)

-Eventually the radio just stopped working and wouldn’t turn on, and ALL the dash lights stayed on while driving, with none of the gauges working, while the odometer reads “error”.

-After about a week of that, I decided to remove the radio. That actually helped alot. The MPH gauge and the RPM gauge now work, the front lights are back to normal. The car starts every time!

-However, the Gas gauge and Temp gauge still don’t work, and the lights are all lit up on the dash and it still reads “ERROR”

I know it can be many things, but what steps can I take to find the “short” or “bad wire” or fix the problem. I know the hard part, is actually figuring out what is causing it. Any Ideas?

I think that you have only one hope which is a loose ground or two someplace. Find all of the grounding points on the entire car and clean and tighten all of them. If you see any signs of bigger worries with them then run a new ground wire.

Short of that, you’re looking at having to wrangle with a GM dealership over a new body control module. You can buy these used and install them yourself, but they have to be reprogrammed at a dealer. And a lot of dealer service depts won’t do anything with used ones.

So keep your fingers crossed for a bad ground someplace.

Wheres the “best” and “first” place I should look? Most guides point me to the main computer cluster to the left of the steering wheel… any methods or tools I can use to find the fault?

That it worked better after removing the radio does point to a wiring problem instead of a bad cluster, though the cluster assy could certainly be bad as well. You might try finding the old radio ground wire and splicing a wire into it, then running it to a good ground connection or some good bare metal on the body. Also it might help to wiggle all the wiring under the dash and see if anything affects your problem. You might localize a loose connection that way.

This isn’t a flood car is it by any chance? The fact that stuff won’t shut off, to me would be more of a short rather than a ground. Feeding power to the circuit from a second source that is hot even when everything is shut off. I don’t know if the BCM could do that or not but would be a major clue. I guess I’d start with the schematic and there is also a diagram in the service manual that would show the actual layout of the wire harnesses. Look for common points, corrosion, pinched wires, etc.