So I know about the worn brushes causing the high rpm cutout, I replaced the brushes about a year ago. Everything has been fine until last weekend. The same symptoms are back. Will a faulty regulator cause the battery light to come on with high rpm?

 

High possibility that you have a brush problem again.
The comutator rings may be burnt or out of round and caused the short life span.
I would either replace them again to see if the problem clears again then expect to get a new OEM alternaor for the next time.

 

Thanks Blue, I'm going to investigate tonight.

 

Just an update, I removed the alternator over the weekend to figure out the problem. I removed the brush holder assembly and was ammazed that one brush was worn beyond the service limit. It was the same brush that was worn out about a year ago. So I put a dial indicator on the comutator to check for an out of round condition. While it was not out of round there was a jump in the needle at the same spot on the comutator every time. Here, there is a defect in he copper that must be acting like a cheese grater to the brush. As for the defect, it looks like an included air bubble in the copper when it was cast. I guess I didn't see it a year ago because it was late at night and quite dark when I was rebilding the alternator. So, I guess it is time for a new alternator.

 

Ford's parts computer may not be 100% correct. They showed that my truck needed a 95A altternator. So I bought one and it was wrong. I had to get the parts manager to look it up with my VIN in a different system to get the engineering number and then it crossed corectly to a 130A alternator. Also, you can tell pretty easily because the body of the 95A is 5 1/8" diamater and the 130A is 5 5/8".