Alternator charging ?

[GIT-R-DONE]

My truck will not charge at idle, but will charge when the motor is @ a higher RPM. Driving down the road it is at full charge, but let off the go pedal, will not.



I have a 1991 intercooled with the voltage regulator on the firewall, ( like the old style mopars). Could this be coming from the voltage regulator or is the alternator going bad. Any ideas?

 

[B.G. Smith]

Sounds like the alternator, probably a bad diode. Some of the parts places have instrument to check unit in place. bg

 

[RedRamAndy]

Agree on the diode in the alternator diagnosis. All my old Mopars had three on the charge side and three on the discharge side. When one went bad out of either set, it would throw all out of balance. If you lost one on the discharge, it would overcharge all the time. Sounds like you may have lost one on the charge side if these alt's are set up like the old ones I've played with. Never been into the one on the Cummins yet.