The Ford Barn - View Single Post - Alternator & ampmeter are fine...NOW WHAT?

Texas Tom · 04-24-2015, 05:33 PM

Yesterday I posted a question about why my ampmeter would not 'excite' when I started the engine and revved it up. Several folks suggested my alternator is likely the problem.

This morning I tested the alternator with a voltmeter and found that when I started the engine, the voltage dropped. This usually indicates a faulty alternator. So I pulled a spare (new) alternator from my parts pile and installed it. Same result!

So I took both alternators to my NAPA store and asked them to test them. Test result: both alternators work just fine. Yikes!

So I'm back to square-one. There is nothing wrong with my alternator, and apparently nothing wrong with my ampmeter (I tried three ampmeters, which yielded identical results: very slight discharge).

So why is my system (12 volts) discharging when the engine is running? I have no clue. Everything worked fine before I took the car out yesterday to give it some exercise.

HELP!

04-24-2015, 05:33 PM	#1
Texas Tom Senior Member Join Date: May 2010 Location: Texas Posts: 137	Alternator & ampmeter are fine...NOW WHAT? Yesterday I posted a question about why my ampmeter would not 'excite' when I started the engine and revved it up. Several folks suggested my alternator is likely the problem. This morning I tested the alternator with a voltmeter and found that when I started the engine, the voltage dropped. This usually indicates a faulty alternator. So I pulled a spare (new) alternator from my parts pile and installed it. Same result! So I took both alternators to my NAPA store and asked them to test them. Test result: both alternators work just fine. Yikes! So I'm back to square-one. There is nothing wrong with my alternator, and apparently nothing wrong with my ampmeter (I tried three ampmeters, which yielded identical results: very slight discharge). So why is my system (12 volts) discharging when the engine is running? I have no clue. Everything worked fine before I took the car out yesterday to give it some exercise. HELP!