I have a 91.5 d250 o/d ,,new alt., new ext./ volt reg., ( actually the 4th v. reg ). 20 deg. here this morning,started trk.,"WHAM" amp gauge peged past 18,, thought it was going to hit speedo gauge. Grabed volt meter, read 17.66-17.89,,,,,let trk., run 20-30 min for warm up,,,drove 3 mi. to town 3 mi. back ,,,no change????????????????Yes !!! it does have a pcm,,i'v been hav'n this problem for a while,,just not this bad.soooooo what would happen if I just up'n cut that little green wire that goes to the pcm,,would this "SOB" ( SOMEBODY OUGHT to BUY") quit-die-rollover or go up in smoke,,.I'v grounded to every thing ,but the direct tv. cable ( the little wife drawed a line)


whosdunit.

 

Does it still overcharge with the regulator unhooked? Could be a bad alternator with a short internally. Could be a bad battery. Could be dirty connections on the battery, alternator, regulator or starter. Could be a bad ground

If you have a external regulator hooked up your PCM has nothing to do with charging anymore

 

To sort this shotgun blast out.......
Regulator unhooked at regulator, tests wire to alternator and alternator, should not charge.

Regulator unhooked at alternator, tests alternator, should not charge.

At 17 plus volts and high current, the battery isn't bad, yet. It'll let you know when the top blows off.

Not dirty connections, except possibly the ground at the regulator.

Could be 'nother bad regulator.

My best guess, it's probably a short to ground in the regulator to alternator wire.

 

PCM doesn't control any charging function on any 91 Diesels, only gassers.

 

Thanks guys,,i'm just blow'n off ,,,,been hit w/ice storm,, got trees down every where. But "J" you may be right about reg., wires , may be tomorrow i'll get to go through wires. I think i'll build some jumper 's and go from alt., to reg( green wire) and go around that black rubber do dad on the alt., i'll holler back ,,thanks ,,whosdunit.

 

On my 91.5, I found that the ignition switch was shot. With bad contacts, the regulator was not "seeing" line voltage even though the alternator was running full tilt. In 92-93, the regulator feed was taken off the ignition switch and put on the auto shutdown relay eliminating that problem, but creating a new one by placing the regulator inside the PCM.

 

Easily tested. Look for battery voltage at the regulator when the ignition switch is on.

 

Just installed different brand of v-reglter, voltage droped to 15.34,,,,,steady even at higher rpm,,battery voltage ,,w/ sw., off 14.43, probly due to being over chged., earlier., Ya'll keep feed'n me info i'll keep try'n. Thanks to each of you.

whosdunit.

 

You might turn your headlights on and run that back down about 13-13.2 where it should be.

 

Or your meter might be off. I own several meters. One is a bit "wild".

 

As long as you leave everything hooked up. The volt meter on its own doesn't put enough of a load on the circuit to show a weak connection.

 

You're right. A test light would put a little load on it.

 

I'm hearing,, all of ya'll ,just bought digital meter a parts house,,( I think I have it set right ),,cked., at batt., & at alt., ( same reading),,then cked., @ heater relays to see if one of them was leak'n( short"n ) cked., under steering colum @ ing., read same as batt.,& alt. I'm pretty sure I have a short ( draw) some where,,,,it's just to dang cold to crawl around out there just now. I think live w/ it for right now. BIG THANKS TO ALL,,,,and "HAPPY NEW YEAR".