I recently purchased a 2000 Monte Carlo SS it was equipped with an aftermarket radio (I still have the stock radio connected in the trunk ). Recently I turned on the windshield wipers and the radio at the same time and they both stopped working. Checked the fuses and they are still good but the voltage has dropped to only 3V's. In checking the whole electrical system it seems the installer taped into one of three 12V switched lines because they are all getting only 3V's to them, BCM, Windshield wipers and the Cigarette/ Aux port. Bad Ground? Fusible link? Any help or ideas would be greatly appreciated.

 

If it was a bad fuseable link, you would have no power at all. Check the ground and make sure its clean and tight. Also, try taking the hack-job wiring off, and see if the voltage comes back up.

 

It turned out to be the ignition switch which apparently goes bad sometimes in these cars. Replaced the ignition switch and all was fixed. Thanks for the help