Engine/Transmission (1998.5 - 2002) Intermittent charging issue

[Will24]

I've read every alternator thread on here, nothing seems to duplicate what I have going on...



First. The grid heaters are not creating my problem.

Second. I am a very with it tech, I am just lost on this problem.



Ok, here goes... I recently purchased a 99 6 speed 4x4 truck as a daily driver. I've gotten most of the bugs worked out of the somewhat neglected truck, but I still have an intermittent charging issue.



Occasionally for no reason whatsoever the alternator will drop out. Battery voltage is maintained fairly well (I have 2 group 31s under the hood), and randomly, voltage comes back up just fine. It's not just the guage, as the headlights noticeably dim when the voltage drops. The problem seems to occur more with the truck warm, and WAY more frequently at highway speeds than around back roads. The past 2 days have been warm in PA, the problem is occurring more and more often. I am I seeing alternator brushes going out? Diodes etc all check out ok on my midtronics charging system analyzer. Anyone run into this situation?





Thanks!

Will (stumped!)

 

[Heavy Hauler 10]

yeah i had the same thing happen to me two weeks ago... every time i pulled it up to the shop it stopped doing... but every other time i went down the road the gauge would fall... i finally got to the point where i was going to pull it off and get it tested but the day i went to do it i had no problems and for the last week and a half nothing not once. i hope for you your problem goes away like mine

 

[SNGLESHOT]

A friend had this problem but in a newer truck, i think his is an 05 3500... and it drove him nuts. he spent a lot of time and unecessary money trying to eliminate what might be the problem voltage regulation system, everything. Even the dealer could not find a problem as it was intermittent like your problem is. end result: he finally had it rebuilt (no details if they found anything) and that fixed the problem but they never did find out what was the cause. this is probablly not much help but at least you know your not alone.
PS: I like the fire truck pic. I am a firefighter from Volant PA, currently stationed at Fort Huachuca AZ for a tour of duty.

 

[Will24]

That pic has been my avatar forever, it's a New Lexington, LOL, soon to be a collectible since they went out of business!



Anyway, ironically enough, I posted my issue last night and this morning my charging system pretty much went inop, great... pulled the alternator off at work and benched it, FINE... .



Great, what now? Dug around a bit... damn, I missed a wiring problem.



Long story short, the Gray wire at the 2 pin field connector om the back of the alt. broke off flush with the back of the connector, the lovely wiring wrap had it pulled in nice and tight though, looked perfect at first glance! I yanked the connector apart and soldered the wire to the terminal (I didn't have the right terminal, so it's fixed either way now... ). Charging system is 100% now... That was frustrating!

 

[blacksheepdiesel]

Glad you found your problem. I had a charging issue where I would put a new alternator on and 50,000 and 6 months later the voltmeter would go to zero with new warning. New alternator fixed the problem. Did that routine 3 times. Finally able to source that small 2 pin plug for the back of the alt and the problem is fixed. I think the plastic inside the plug was so worn from vibration (after 600,xxx miles at the time) that the pins on a new alternator would make contact for a while and then get worn enough that it would break current.

Godspeed,
Trent