2000 Ford150 Supercrew, 4.6L, Auto, 4x4, 135Kmi

My dash battery warning light intermittently comes on at any random RPM above idle. At idle it almost never comes on. Sometimes it blinks and sometimnes it stays on for minutes while on the freeway.

Here's what I've done.
--Replaced my old battery with new one.
--If I remove the negative battery cable the engine dies. Not sure if that diagnostic trick applies to these newer vehicles.
--Battery voltage while idling is 13.9volts. So alternator does have some output.
--Cleaned alternator connections.

Any thing alse I should check?

 

Replace the alternator, sounds like a bad diode

 

Is the diode inside the alternator or can I just replace the voltage regulator thats attached to it?

 

you would have a very hard time finding parts for an alternator...its just not done that way anymore...get a remanufactured unit from a parts store.

 

I replaced the Alternator and problem is gone. Was $139 with Lifetime warranty.

 

right on