Hi Everyone! I have a '71 Mav, 200 engine. I have one or several problems with the electrical system: When I shift into "R", the radio goes out. It's not a factory radio, but it is old...it has a cassette player! The other problem: With the headlights on or when pressing the brake pedal, the turn signal relay goes very slowly. I took the car to a shop, they checked the alternator, with the engine on--but not in gear, which would represent a real driving condition. I can't imaging an accurate test without the car in gear. Sometime ago, I replaced the alternator and at the same time, the voltage regulator--the replacement regulator is a Motorcraft. The car isn't driven very much, so I find it hard to believe that either could be bad. Thank you! Bye, Daniel W (Renton 5)
Have your battery tested. Charging system at very low idle (like in gear waiting at a stop sign) is pretty much non-existent. If battery is all good and charging system is functioning properly, you will need to isolate a high current draw somewhere in the system.
Potentially, HALF of the electrical problems that are out there are bad grounds. You need power and a ground to make a circuit. Check the ground wire going to the motor and all of them going to the chassis to see if they are snug. Any chance you cleaned and painted some areas and then put the ground back on, on top of fresh paint? Food for thought ... Like mentioned above, old alternators at idle had very low output. Newer models tend to be better in that respect.
You didn’t say if the charging system passed or failed the test. As others mentioned it sounds like a ground issue. I would remove and clean all grounds, big and small. If your HI-FI was “old” it would have a 8 track!
Thank you Acornridgeman, Miguel, Captain Comet, and BBMS18! I'm thankful that the car, since it's so (relatively) simple, won't have too many ground points to check! I'm not very knowledgeable on electronics, but wouldn't a bad or loose ground connection cause the turn signal relay to function slowly, even without any other pull on the electrical (like brakes being applied)? Is there anything else besides the alternator and voltage regulator that could affect electrical output based on idle speed? Bye, Daniel (Renton5)
Measure battery voltage(at battery) at idle with heater blower at max and headlights on high beam. If it's around 13v that's OK. Next do same with car in gear(be sure to set brake and block wheels). As already stated voltage is likely falling at that point, below 12v you probably have a iffy battery. Be sure regulator is tightly mounted.
