I have a 2001 Monte Carlo 3.4 L that is having intermittent electrical issues. The temperature gauge will stop working from time to time but if I reset the car by taking the negative battery cable off and then back on, it will work fine...for a while. Then the radio will decide not to let sound out of speakers even though it is on...then randomly will start working again. Then the dash lights might decide not to work for a day or two, but then mysteriously work fine. Now my transmission is acting goofy...lower gears switching rough; next day lower gears are fine but won't shift into overdrive on the highway. Could this be a computer problem such as the ECM/PCM? Please help!

 

Jay:
Sounds like it could be a possible ground issue...
I'd check clean all your battery connections..
Followed by checking/cleaning all your body/chassis Grounds..

 

I agree with Stumpmi, check all your grounds. I would also check your Body Control Module. It controls a lot of those things. Better to check it now then wait until it the stops running!

 

Thanks for the advice! Is there a good way to check the body control module to determine if it is good or bad?

 

Below the air intake is a common ground that corrodes. Start there

 

You need a Tech II scanner to check the BMC, ABS, and Transmission!