my truck started doing this about a month ago. pulling the camper to the lake and i noticed my voltage guage dropping. continued to drop to nothing and check guages light came on. pulled over and shut truck off, started it back up and everything was fine for a couple of miles. limped truck home and looked over wiring and found a ground wire that was against the alternator housing had rubbed through slightly. sealed it up and everything was fine, for a couple of weeks. problem came back worse than ever. i replaced all of the battery cables, checked all of the grounds. i have an edge juice with attitude that shows my battery voltage, i noticed when the charging systems quits and the voltage meter drops to nothing and the check guages light comes on my edge shows the alternator is charging sometimes like normal, but normally very erratic. when the system is charging normal it is around 13.5 to 14.1 volts, when it is acting up it, it goes from 12.1 volts (batteries) to 14.1 (alternator charging) and everywhere in between. had the alternator tested and of course it tested good. i wonder if i should put in an external regulator. if you have any ideas they would be greatly appreciated!!!!

 

you need to update your sig so people can see what the truck is. I remember on my 07 (3rd gen) there was a wire that commonly rubbed through on a line from the a/c compressor that caused a bunch of issues. thats where i would start but like i say, need to know what truck it is first. you can update your sig in the user CP tab at the top left of the page.

 

sorry i never did fill that part out when i joined. 2001 2500 24 valve ho, six speed, edge attitude w/juice, straight pipe, jacobsen exhaust brake.

 

checked every wire that could possibly be touching something and did not find any that were rubbed through.

 

If its the original alternator, it is possible that the brushes are hanging up and causing it to skip out on you. I think if the ECM senses that alternator is out of control it shuts it down.

I've had a similar problem with my 97 and I've replaced the brushes myself not a hard job.

http://www.fostertruck.com/alternators.htm

 

thanks for the info, i didn't think about the brushes. that alternator has 175,000 miles on it. i will open it up and take a look. thanks again!

 

My 96 did that it was brushes and diode pack. Suggestion, have your alt rebuilt don't get a rebuild from a parts store.

Floyd

 

If it's intermittent like that I wouldn't throw an external reg. on it yet, probably something in the alt getting hot. The computer stopped controlling the alt. on mine a few months ago, but it just quit while idling. Thought for sure it was the "parts store" alt that had 110k on it, swapped it out to the same symptom. Rang out wires right back to PCM connectors and everything was fine, put an external regulator on it and it's good now. I'd rather it be a factory setup though.

 

The alternator doesn't have that much going on in it. Fixing it was a breeze. My first alternator had too much wear on the copper running surfaces for the brush kit to last more than a year and I had to get a new Alternator to fix that or pull it apart myself. The brush kit was cheap and took about and hour to R&R it. Almost worth getting two sets and throwing one in the consol for a rainy day.

 

thanks for your help everybody. i took the brushes out and they were down to the nubs and the commutator was worn almost through the copper. bought a new alternator and that fixed it. thanks again.

 

That copper ring, slip ring, collector ring is replaceable.

 

I was told it was a press fit on to the rotor and would need to be soldered in as well. I didn't think it was worth the effort. Have you done that replacement?

 

Yeah, I'm curious about replacing the slip rings too. My alternator is still original, and I've replaced the brushes and rectifier. I smoothed out the slip rings as well as I could, but I know it isn't permanent. I just assumed I'd have to replace the whole rotor when the time comes. Do the old slip rings get machined off with a lathe, then the new ones get pressed on, or how does the replacement work? Has anyone done it?

 

My thoughts exactly... Anyone?

 

I had mine done @ an auto electrical shop, the slip ring, the whole rebuild, about four years ago, cost $80 has worked great ever since.

Floyd