97 GMC Jimmy charging/alternator problems

i have a 97 gmc jimmy 110k miles. going down i-95, battery light comes on, voltage drops to 10, alternator isnt charging, battery is swelled up...

i replaced the battery and alternator, all is working... next day go to work 30 min drive, coming home, same ordeal again... pull alternator take it to autozone they test it, it's fried... get another new one... next day same thing happens... so i decide to investigate. seems that at idle it's getting hot and smells... i unplug the connector for power to the voltage regulator and it stops burning, smell stops, it cools down...

my thoughts are either regulator is getting too much voltage, mabye a switch stuck open? or there is a short or something drawing too many amps?

if anyone else has run into the problem please share your experience :) im trying to avoid ripping all the wiring harness apart...

Thanks! :iceslolan

have you ever replaced your belt tensioner?



i have a 97 gmc jimmy 110k miles. going down i-95, battery light comes on, voltage drops to 10, alternator isnt charging, battery is swelled up...

i replaced the battery and alternator, all is working... next day go to work 30 min drive, coming home, same ordeal again... pull alternator take it to autozone they test it, it's fried... get another new one... next day same thing happens... so i decide to investigate. seems that at idle it's getting hot and smells... i unplug the connector for power to the voltage regulator and it stops burning, smell stops, it cools down...

my thoughts are either regulator is getting too much voltage, mabye a switch stuck open? or there is a short or something drawing too many amps?

if anyone else has run into the problem please share your experience :) im trying to avoid ripping all the wiring harness apart...

Thanks! :iceslolan

have you ever replaced your belt tensioner?

yeap was replaced awhile ago. it's not like its not spinning, its just something is getting it way too hot, coil turns black and burns out.

I would go another brand of alternator.
Could be a bad batch at AZ.
After you get a good alternator installed make sure the battery is charged up before running engine.
Then get a volt meter or charging system tester on it and make sure it is not overcharging.
MT

okay got a brand new one... not remand from a different store and different brand. still doing the same thing, when i plug in voltage to the regulator it kicks in, then it starts to get hot and i can smell the coil burning. on the old one the coil was deffo burn out, all the coating is melted off the coil wires and turned black...

mabye ECM/PCM is keeping the regulator on too long or all the time? none of the fusable links are dead so i assume nothing is pulling too many amps...

still clueless.

okay got a brand new one... not remand from a different store and different brand. still doing the same thing, when i plug in voltage to the regulator it kicks in, then it starts to get hot and i can smell the coil burning. on the old one the coil was defoe burn out, all the coating is melted off the coil wires and turned black...

maybe ECM/PCM is keeping the regulator on too long or all the time? none of the fusible links are dead so i assume nothing is pulling too many amps...

still clueless.

A alternator will run hot to the touch and a new one may smell some.

Make sure battery is full charged and cables are good and clean.
What is the voltage reading at idle and 2K rpm.

How many small wires are on the back of it.
Alt light or amp gauge on dash?
I do not show any PCM control on it?
Are you running any high amp stero stuff?
Also check your charging amps at idle and at 2K.
MT

on the back there's 1 connector with 1 brown wire for power to the regulator, and then there is the main stud on the back which has 3 wires connected to it, 1 to the battery, and 2 that go into the main harness, all 3 have fusable links built in.

with the burnt out alternator the battery light comes on in the dash, volt gauge doesnt move off 12

with good alty it charges at just above 14, no battery light

everything is stock, radio, AC, etc...

waiting on an amp gauge to test current coming off the alty, but seems like w/e controls the regulator is not functioning... cus with alty disconnected it runs off battery and is able to sustain voltage so...

Regulator is built into alternator.
14 volts engine run is good.
But I like to see a little more or closer to 14.4 to 14.5

What are you disconnecting to run off battery?
With alt unpluged you should only see battery voltage.
What is battery voltage before starting and after starting?

battery voltage is around 12

here's some pics of one of the reman'd alternators that burned out...

http://www.bt-chat.com/junk/IMG_0090.JPG
http://www.bt-chat.com/junk/IMG_0091.JPG
http://www.bt-chat.com/junk/IMG_0092.JPG
http://www.bt-chat.com/junk/IMG_0093.JPG

A good full charged battery should be 13 or a little more volts.
Are you sure battery is good and fully charged before starting up.
Trying to charge a bad or low battery with the alt will sometimes fry alt.
What is the charging voltage and amp reading?
Most parts places will test the charging system on the car/truck and see what it is doing.
MT

charging voltage is 14.5v

got a new battery, seems to not heat up as fast... will road test and see what happens

were there any options when you bought the first alt. 60 amp 80 amp 110 amp??

remand alt was 105 amp, stock i guess

new one is 110 amp, stock replacement, just 100% new


EDIT: FIXED! new battery was bad, acid test says fail. was prolly refusing to charge.