This is my first post here, been lurking for a while. I just picked up a 92 flareside 5.0L, E4OD 2WD. I got it to tow my motorcycle trailer. The truck runs good but tonight I started it and noticed the lights were brighter than normal. The battery guage on the dash was pegged at 18+ volts. I had to drive about 10 miles to get home. On the way I noticed that when I came to a stop the guage went down to normal and the lights dimmed slightly. As soon as I started moving the guage pegged again and the lights got brighter. This continued the rest of the way home. Any ideas what this could be? The alternator was changed when I bought the truck two weeks ago. Any ideas welcomed.

 

I think you got a bad alternator. There is an internal voltage regulator, if it goes bad the alternator would need to be changed. Have the auto parts store test it.

 

That's what I was thinking. I'll get it checked tomorrow. I'll post what I find out. Thanks for the quick response.

 

Replaced the alternator and all is well. Thanks for the help.