My son recently purchased a 99 blazer, and it has some ‘issues.’ When he purchased it, the vehicle didn’t have a radio installed, and the harness was cut off. We installed a new radio, and suddenly, the interior lighting began to work again. Now, however, we have noticed that when he presses the brake pedal, the dash lights dim, and the radio cuts out for a second. It seems like a voltage drop.

We noticed that there was a loose ground—actually hanging down—in the very front passenger’s side under the battery. It was in the string of headlight wiring. We didn’t see exactly where it came from, so we picked a spot behind the front headlight, attached it there, and checked the continuity—was good, but didn’t change the radio issue.

Also, the power mirrors don’t work, but the fuses are good. And finally, we noticed that someone has completely cut off one of the O2 sensor connectors.

The vehicle has issues.

I was hoping for some suggestions on where to start with troubleshooting these problems. The most annoying thing for him is the radio cutting out, but that may be small potatoes compared to what else is going on.

I looked a bit in the forums and saw something about smoothing out voltage issues with an additional wire on the alternator harness. Would this be a good thing to try first? Where should I begin?

Thanks for advice and suggestions.

 

power mirrors, switch could be worn out. Mine doesn't really work either unless i tap at it and hit it in all different directions. A new switch should fix that.

 

Thanks for the suggestion about the switch. That is a little further down on our priority list at the moment. I guess we'll start by pulling the alternator and having it checked--I understand that the voltage regulator is built in. After that, I'm not sure where to go. I wouldn't think the missing O2 harness would cause this type of thing, but ????

 

You could look at that cut-off harness to make sure the wires aren't grounding anywhere, but I would think that would only cause engine problems or throw codes. But it's worth a check.