Hello, Just got an 84 S-10 blazer with the V6 for my son. If we jump the car, it starts, runs and drives just fine. However, the battery (new battery) will not take a charge while driving, and when a battery charger is connected, there is a humming or buzzing noise coming from under the dash near the headlight switch. When the brake is pressed, or the headlights are turned on, the noise stops.

I am going to remove the alternator and the battery to go and have them tested, but I feel pretty confident they are OK. Any other suggestions?