Alternator Problem

[bobcoop06]

My alternator has been whining a lot lately, and finally went out last week. I figured a bearning went out (the car has almost 150K on it), so I went to a junkyard and grabbed one off of a wrecked car with just under 12K on it. Got it home and put it in, and the gauges started going crazy come to find out, that one had a diode shorted out. So I got another alternator, again a used but still fairly new one (19K). Got home and put it on, and nothing. The battery light stayed on and it still doesn't charge the battery. I had the alternator tested and it works fine. I tested the battery, it's only 3 months old and is fine. I put a new belt on and checked the fuse for the alternator, it was good. I don't know where to start now, I've done quick checks for loose wires and can't find any. Could the tensioner be bad? Everything else seems to work fine... It's a '98 P71 with 150K miles on it. Any help is appreciated.

Thanks!

[fleettech]

what year did the new used one come off of ? it makes a difference if it works or not

[bobcoop06]

Originally Posted by fleettech

what year did the new used one come off of ? it makes a difference if it works or not

A 2003. Everything (including the wiring harness) fit perfectly, no jimmy-rigging required (this time).

[fleettech]

a 2003 alternator will not work on a 98 they changed the way they work and the pcm controls them now. yes they will bolt up and plug in but they won't charge.

[way2old]

fleettech is correct on this. Get an alternator from one that is within 1 or 2 years of yours. I think 2003 was the change over year.

[bruzer321]

not to be an ass or anything, but just man up and get one from pep-boys or auto zone they will give you the exact one no guessing and some come with a lifetime warrenty and i dunno about the new vic's but i know the old ones wee known to eat alternators, yea its more money up front but its less hassle, work, and most important less time involved now and down the road