Low voltage in 3 wires
 

I have recently bought a 2000 Monte Carlo SS with an aftermarket radio. I went to use the Windshield wipers and the radio went. I then went through the electrical system and found that at the fuse box the BCM, Windshield wiper, and Cig/Aux port are all only getting 3V's of power but fuses are still good. I was wondering if anyone had any ideas about the problem? Any diagrams?

Check the battery connections before yu do anything else, along with the cables. Sounds like there is a bad cable somewhere.

Turned out to be the ignition switch power wires going in where at 12.8 and the effected wires coming out where only 3V's.