losing voltage at high rpm

[MFerioli]

I'm showing a lower or maybe zero alternator output when I'm running in the higher rpm range. The battery gauge shows a definitive drop and the lights dim. It seems to happen when accelerating through the gears and also when at highway speeds and in 4th. I also have a squeal that shows up when its raining or just moist out. I checked to see if the belt was really loose, but seemed ok. Is there a bolt on voltage regulator on this truck? Could that even be the problem? Thanks for any thoughts.

Mike

2000 3.0 xlt Ranger

 

[Plum Ranger XLT]

If you could, take your alternator to a local auto parts store and have them test it to see if that is your problem.

 

[Wicked_Sludge]

thats what i would do.

it sounds like the loose belt is probably more likely to be the problem though. a new belt and tensioner should fix it right up.

 

[vpetersen]

I have a '99 3.0 and it started with this same problem last night. If I sit with it in neutral and rev it up to around 4k rpm the alternator appears to stop charging. The lights dim, battery light comes on, and the volts gage drops. It does this while driving too, that is if the engine is reved to 4k rpm. At first I thought it was a sign that the alternator was on its way out, but I guess it could be the belt too. Maybe I'll try a new belt first and see if that cures the problem.

 

[Beef52751]

mine did the same thing, it was the alternator
Beef

 

[vpetersen]

good to know, I'll just replace the alternator then.

 

[Wicked_Sludge]

then you'll waste money when it turns out to be a slipping belt

parts stores will test the alternator for FREE so you dont end up replacing a good alternator.

 

[MFerioli]

Thanks guys, I'll have the parts store check first before I do anything else. I'll let ya know what they find.

 

[MFerioli]

I pulled the alternator, they said it checked out fime at the parts store. But when I pulled the voltage regulator off, one of the brushes was in really bad shape. I got a used one at the junk yard and so far things seem to be working just fine.

Thanks for the help,
Mike