i have a 2002 f150 extendend cab V6 5 speed and for some reason when the engine runs higher rpm (like when i get on it while passing somebody) my battery light comes on i have 200250 miles it has a newer alternator and battery any idea whats going on?

 

Yes, I know you said they are fairly new, but I'd still go get the battery and alternator tested.

 

maybe belt slipping...but sounds like the alt or batt is causing you a mishap...try cleaning terminals too??

 

I would say it would be your belt are alternator.

 

ok i went ahead and replaced the battery alternator and the belt how ever it is still acting up at high rpms

 

Pretty sure you are having the same issue I had a while back. It was in deed a bad alternator. The voltage regulator to be specific. Take a Digital volt ohm meter (Fluke Meter) and check voltage at the battery. Rev the engine while you have the fluke hooked up and watch for voltage to spike. Mine was hitting about 19V at 4000RPM.

When you buy a new alternator, dont be a tight wad buy the new one instead of remanufactured. If you have to go remanufactured either buy it at the dealer or take yours to a local rebuild shop and specify that they go all through it. The ones you get at autozone and places like that are not quality rebuilds. Most of the time they replace the brushes and diodes and call it good. If you have the problem i think you have it wont be fixed by those means. Thats about the best I got.

shawn

 

Did you replace the battery and alternator without getting them tested first? Throwing parts at a problem like that can get expensive.........

 

The guy at autozone said they were both good but i had a valucraft battery in there so i replaced it with a duralast gold the alternator shows it was good but i have heard they can be bad and showgood on the computer so i replaced them both i changed the serpintine belt about a month ago i used a gatorback belt and i try to keep dressing on it and i try not to go cheap

 

You should NOT use belt dressing on a Gatorback - or any other serpentine belt.

 

The guy at autozone said use a half a can every oil change i gues he was just trying to take my money, anyone know where i can get a split rear window for my truck?