STALLS, RADIO/FRONT WINDOWS INTERMITTENTLY LOSE POWER
2000 Pontiac Grand Prix
June, 28, 2012 AT 2:55 PM
My car will drive for miles (longest recent drive was 20mi) and then suddenly begin having problems. Yesterday -after driving for 15min- the aftermarket radio began to lose power at idle. I turned it up, it turned itself down 3 times. A few hours later, I stopped at a light & the car stalled out. I removed the radio face plate just in case, it immediately started back up & ran the last 2 miles of the drive. A week ago, I lost power to the driver's window. The passenger window has never worked, replaced motor to no avail. I believe this all points to electrical issues, but wanted a more informed opinion before I start digging around in the engine compartment.
These could be two separate problems but start by checking the wires between the door hinges. A broken wire can stop a window from working. If the radio power wire is connected to the power window circuit, a frayed wire could be touching another wire and affecting what ever else it tied to it.
When the problem is occurring, measure the battery voltage with the engine running at idle. It must be between 13.75 and 14.75 volts. If it's low but comes up when you raise engine speed, suspect a defective diode in the generator. A professional load test will verify that. The generator could also be quitting intermittently. In that case you'll find battery voltage near 12.6 volts with the engine running.