I have a 99 ranger 3.0 XLT 4x4. My voltage gauge drops pretty low and the battery warning light flickers whenever I quickly accelerate (drops happens around 3000 rpm's) or whenever I go up a steep hill. I had the charging system and battery checked at two diffrent places and both said that everything was fine. At the second test place I was revving the engine up past 3000 rpm's during the test and I could see the voltage gauge drop very low but the test still came out okay???. I checked all of the wiring connections (battery and alternator) and everything appears tight. Would removing the alternator and having it tested on a bench tester be more accurate? Any suggestions on how to proceed would be most appreciated!

 

have u tried cleaning the terminal posts? that could help

 

Dirty terminals aren't going to change anything with RPM. Your alternator has to be on the way out. Are these places testing with it still attached to the truck or are they taking it out? The only other possibility is the belt slipping and you aren't noticing it.

 

Agreed. With a 99, especially a stock alternator, the slip ring brushes are probably gone. That or a ed connection in the rotor (which happened to me).

I'd replace the alternator, or if you really don't want to go that far you can try replacing the regulator and brush assembly on the alternator.

 

Happened with mine a few years ago. Everything tested fine but I went out on a limb and changed the alternator to be sure, it worked. Change the alternator and this should cure your problem.

 

Definately Alternator. Mabe the guts of an Interceptor packaged Crown vic will fit the alternator {200 amps}

 

Thanks for all of the advice. I just got finished replacing the alternator as suggested and it test drove fine. No more voltage drop at any RPM. It would have helped to have an extra pair of hands putting the belt back on but after a couple of busted knuckles and a little cursing I got it back on!! Thanks again