More %#@! Electrical problems

[haggis6145]

I recently installed 2 new batteries on my 1986 m1028. Blew some fuses and my two new headlights. Turns out the system was providing 17-18 volts. My mechanic disconnected a wire from the regulator(?) on my upper alternator. He said it was then charging fine. As time went on, the accessories (turn signals, wipers) got slower and slower. Finally, no juice to start the truck. I was unable to test both batteries to determine if both were dead, or only one. The gauge (yeah, I know..) indicates the system is charging. I suspect a regulator problem. Any thoughts????? Please offer any suggestions because this truck is driving me #$%@! crazy!.

 

[Westech]

My mechanic disconnected a wire from the regulator(?)...there is your problem. You sure he or she knows how to work on a cucv? I bet they messed it up.

 

[haggis6145]

Yeah, I hear what you're saying. If it's meant to be connected, it should be connected. I'm no mechanic myself, but trying to find a tech that understands these trucks up in the Great White North ain't easy. Trial and error has been the process so far.

 

[Mudstone]

check your driver side alt. for a black wire that should be grounded to a bolt near the intake manifold bolts. that IS bad on my truck and it doesn't charge efficiently. just my something to check... and a REALLY cheap fix

 

[haggis6145]

I'll do that. Thanks brother.

 

[ida34]

Sounds like he did not know what the isolated ground was. Ask him about it. If he looks at you with a blank look take the alternators to another place to have them checked by someone that understands what an isolated ground is.

 

[Mudstone]

don't bother taking it to him just look at the back of your driver side alt there should be a black wire attached to the alternator and a bolt on the head.

 

[Crash_AF]

You mention 'upper alternator', do you have an A/C compressor on the driver's side and two alternators on the passenger's side? If so, you don't have a standard CUCV system, you have the 1010 Ambulance style system with the Duvac controller, which is a problematic system and completely different animal.

Later,
Joe

EDIT: I just read your earlier posts, yea, you have the Duvac style system, not the standard CUCV system. These things are a nightmare and have been since they were new causing cooked batteries, fried systems from overvoltage, and in worst case scenarios underhood fires. The best solution that I have seen is to get rid of the 'blue box' on the driver's fenderwell and replace it with a 24V to 12V converter to run the rest of the truck, leaving the alternators to produce straight 24V. There are several other intermediate options that you can search for by doing a search for Duvac, but my personal recommendation is to go the convertor route.

 

[haggis6145]

Hey guys. Thanks for the quick replies. Got some direction now. Any other thoughts, keep em coming. SS rocks!

 

[Mudstone]

what is this DUVAC you speak of and how do i make sure i never see it hear it or have anything to do with it.

 

[Crash_AF]

The Duvac system is in the 1010 ambulances and some late 1028s. Most that I have seen are the 86's but there might be some earlier ones too.

The Duvac system is a 200 amp 24V system with two 24V alternators in parallel instead of two 12V alternators in series. The Duvac controller is a blue box on the driver's fenderwell that was supposed to regulate the upper alternator's output to 14V. The system was problematic from the start and I've never seen one that completely worked well (although it is rumored that there are a couple of trucks here on SS that do) and several incidents with the Duvac control box catching on fire were reported and the system was changed with the 'orange wire mod' by the military. That didn't completely solve the charging problems, but did solve the fires.

Here is a link to a SS thread where the Duvac was replaced by a convertor:
http://www.steelsoldiers.com/electrical/37909-m1010-no-more-duvac.html

Oh, and DUVAC stands for 'DUal Voltage Alternator Control'

Later,
Joe

 

[haggis6145]

M1028 still not charging

OK, so in addition to the new batteries and belts, I replaced the duvac 'blue box'. The mechanic says I am now getting a consistent 14.4 volts. Great, but the front battery is still not charging and drains daily. What the #$@%! Any more ideas would be appreciated.

P.S. I've had it with this truck As soon as it's fixed, it goes up for sale.