The four rear speakers in my 1996 suburban will no longer produce sound. Actually, they will but I have to turn the volume all the way up and even then it just barely comes through. I thought the problem was with the power amp (model # 16211311) located under the drivers seat. I replaced it but still no sound. I pulled the amp off and checked pin voltages on the radio side. The hot has full voltage but the 4 pins for the 4 speakers barely lit up the bulb in my probe. Any ideas?

 

The speaker wires aren't going to light up a test probe, they are not outputting line voltage - only analog sound voltage.

My guess is the problem is upstream. The amplifier section of your head unit may be bad. The power amp can't amplify what isn't there.

 

Thanks VanGo. So, if the problem is at the radio then I'm looking at replacing the factory unit? I assume that they can't economically be repaired.

 

Don't replace it on what I say. It's just an educated guess. Can you plug an old speaker into the input side of the power amp where the channels come in and see what you get?

If it is bad, I'd look for a nicer replacement unit.