Auto Electronics: Charging Problem, plymouth satellite, positive cable


Question
I have a 72 Plymouth Satellite with a 440 in it, Im having trouble getting it to hold a charge. The alternator had tested good repeatedly, I have replace the voltage regulator AND the battery and just cant think of anything else. (my guage in the car shows between dead and charged) My way of testing this is I am cranking the car and pulling the (positive)connector off the battery that is connected to the motor as im sure you know and it dies, from what I understand it shouldn't because once the motor is running it should be running off the alternator not the battery. Please HELP! Thanks

Answer
Amanda, Disconnecting the positive cable to test the charging system, is an old trick that works well on these older vehicles, but not one I would try on a late model. Newer vehicles abound with computers and as we all know, computers aren’t happy when power is abruptly removed. Having said that, it is obvious that the charging system in your Plymouth is not functioning properly. The battery is the first place to start and you have already replaced that. The alternator has tested good, I presume off the vehicle on a test machine, and with a new regulator in place that leaves the wiring as the prime suspect. Most wiring problems occur in the B+ circuit, the output connection from the alternator to the battery. Loading this connection is the most sure way of testing. Otherwise, visually check every inch of this cable to ensure no bad connections or opens. A fuse link is used to protect the cable and battery, it can usually be found wrapped in insulation somewhere near the battery, a bad link will pull apart with ease. Next check the field connection from the alternator to the voltage regulator, this is marked F at the alternator. Again opens, shorts or bad connections anywhere in this circuit are trouble.
Good luck troubleshooting. Don