I have a 93 Nissan 240sx that exhibits weird electrical behavior. I’ve had the battery and alternator checked at two local Advance Auto Parts locations with results indicating no problems.
The car starts and drives fine. Immediately after start, my automatic seatbelts are engaged and the RPMs drop to about 400 and the car shakes violently (while pressing brakes and even when not pressing brakes). RPMs drop anytime accessories are in use. When braking at a stop light, the RPMs drop and the car shakes again. Using my headlights causes the RPMs to drop but not a point where I feel shaking. The problem is worst at night when I am pulling up to my apartment complex with lights on, braking, and using my power windows to access my gate card reader. I don’t know if this problem is related, but when I am listening to the radio and turn the volume all the way up, the radio keeps cuts on and off. I have a suspicion it’s the grounds, but before I start tracing all my wires. I’d like to hear everyone’s input. I determined it was the brake booster vacuum because it alsp happens when not using the brakes and pinching the line has no effect on idle.