M1008 Alternator problem

[adamB]

I have an M1008 that was having problems with the alternators (overcharging).

I had them both re-built and now when I am trying to put them back in I get a meltdown at the wire that connects the passenger side alternator to the 12V junction block near the glow plug resistors when I hook the batteries up.

I have reviewed the wiring and everything seems correct. Drivers side ground to block, passenger ground to junction block.

Any ideas about this?

I suck at electric and am going to just do a 12V conversion if I can't figure this out. This is driving me nuts!

Thanks in advance. I found some old posts with a google search that were supposed to have a bunch of pics but the links are dead.

http://www.google.com/search?q=cach...:www.steelsoldiers.com+cucv+alternators&hl=en

 

[mangus580]

Adam, take a look at these pics, and tell me if they help.

 

[adamB]

Nice pics.
Thanks for the pics.

Mine is wired similar to yours.

Where does the second wire on the drivers ground go?

I have a condensor? attached to the "nipple" on my passenger side alt. and you have two wires coming from the pos terminal on the alt where I only have one. The 8 gauge goes to the positive terminal junction block. Where does the other go?

Thanks again

 

[mangus580]

Adam, have you looked at the Unit Maintenance TM here on SS?

 

[mangus580]

Other thing you might want to make sure.... that the cases of your alternators have not been grounded. These alternators have an isolated ground on them. That could be the cause of your problem too.

 

[85-m1028]

you may have reversed the red wires on passenger side alt. disconnect all wires on the passenger alt , take a voltmeter and check the voltage on each wire the one measuring closest to 12v goes to the ground on the passenger alt along with the condenser, the one closest to 24v goes to the positive of the passenger alt, remember the two blue big blue wires going up to the terminal block by the glow plug resistor are the drivers side alt positive, one comming from the drivers alt the other going to the negative or input of the passenger alt. also make sure the smaller terminal block is connected to the negative side of the front battery and not to the main terminal or 24v block, do both of the "gen" dash lights come on and go off after the truck is started??

 

[n1vbn]

Gents,

CUCV Electrics 101 part 2

The drivers side alternator ground stud goes to ground as it charges the number one batter (next to radiator).

The passenger side alternator gets power from the number one alternator fed into the ground stud....take a multimeter and check the voltage with the two red wires dissconnected from the number two alternator. In the pic of the passenger alternator you see two red wires BOTH ARE HOT Use the multimeter to check the voltage BEFORE YOU APPLY THEM TO THE ALTERNATOR.

The one with 12 volts goes to the ground stud.

The red wire with 24 volts goes to the battery terminal on the passenger side alternator.

To reiterate alternator number one (drivers) generates 14-14.5 volts which is split. One connection goes to the front number one battery the other side of the split goes to the isolated ground stud of alternator number two on the passenger side. This feeds 14 volts to alternator number two which adds 14 volts of it's own and ouputs 28-30 volts to the positive 24 volt bus bar (top) on the passenger side firewall.

Last but not least is the very good possibilitie that you fried the alternators by too much voltage to ground. Hook em PROPERLY this time and cross your fingers.


REMEMBER A 12/24 VOLT SYSTEM ON A CUCV USES THE GROUND ON THE DRIVERS SIDE ONLY.