Folks, I need some advice on what I can check. When climbing a hill or under hard acceleration where I get the revs up above about 3.3K; I will get a warning tone + battery light + the "Check Charging System" message. This combination will flash on so briefly, that I can barely read the Msg, but will continue until the revs drops below 3K.

Haven't tried to replicate the problem while stationary.

Suggested starting points? The vehicle is an 03 Expy EB 5.4


Thanks.

 

Worn or dirty alternator brushes.

When this happened to me I disassembled the alternator and cleaned the brushes and stator. I polished the stator contacts and brush ends gently with a wire wheel. I then put it all back together and the problem was gone.

 

Had to go and look for it, but I knew I wrote up a DIY post about this: https://www.ford-trucks.com/forums/1...ery-light.html

 

Yep alloro is correct. Alternator needs replacing or rebuilding.

 

Could it be the belt slipping under load or at higher rpm's? Change the belt if you do re-build alternator.

 

I know this is an old thread but similar issue here. I had a coolant hose blow out and saturated everything. It blew out directly at the altenator. Fixed the hose filled up the collant and parked it. The next morning my wife says that the battery light came on, and it was acting like it wanted to die. It wouldnt start so I jumped it and it starts fine now. when the rpms go up the volt meter in the dash goes all the way up abs light comes on heat and radio turn on and off. When rpms drop everything goes back to normal. Could all the coolant shooting into the altenator have messed it up? It seems to be charging fine its just spiking. Any suggestions??

 

Try cleaning the regulator connection.

 

It's highly likely the coolant shorted out the regulator circuit and blew the regulator.

 

sounds like a regulator issue, id agree with a rebuild/ replacement. either that or a bad ground somewhere. any hesitations?