I have a 2001 Pontiac Grand Prix GTP. I also have a custom stereo system, professionally installed, with 2 amps, 4x75 for inside speakers and another low one for the sub. By no means a competition system. A few months ago I started noticing that the boost gauge light area & the stereo would shut off and the door locks would lock/unlock intermittently, and right before coming back on I would hear a beeping noise.
I was thinking it maybe from the stereo, so I disconnected the battery ground and sanded the paint clean from an area right behind the center pull down on back seat, drilled a hole and re-screwed the amp ground wires. I was also dealing with alternator whine at the time also. I took the dash apart and checked all the wires and also redid the stereo ground connection more securely behind the radio. I checked the power wires tapping into box above battery and made sure all the fuses on the wires were wrapped in electrical tape.
I did this because I noticed if I went over and uneven area of the street while the issues happened, the boost lights flickered in tandem with the road. After this, the alternator whine stopped and the car seemed fine for 2 weeks.
Last night I was driving to a friends and the same issues happened again, only worse. Now on top of the other situations the headlights would turn on and off and when I came to a complete stop and tried to accelerate again, the car seemed to have no power. It would very lightly jerk a bit and if I pressed on gas the car would rev up to 3k rpm and crawl to 30 mph and then finally drive and shift normally.
Over last 3 years I have replaced the ignition switch, the alternator, and the battery. Im really lost as to where to check because all wires seem good so where would it short from? I tested the ignition switch while all issues were happening and they lit up, then I tested the radio fuse and got nothing. I went to Auto zone and they got the following dtc's:
DTC P0719 Torque Converter Switch B Low Circuit
DTC P0560 System Voltage
Ive been to 2 shops and no one can figure it out.
Originally Posted by mars5l
