alts not charging

[trooper632]

Hey guys, m1009 had the gen 1 light on but dull, I was driving and got into it from about 10mph untill third gear and all of a sudden the gen 1 light went out and has stayed out. problem is that, the alts are not charging. I drive the truck about 40-50 miles during the daytime and it drains the batteries. I have to put them on the charger overnight to start the truck. Before this problem I could touch a screw driver to the back round thing on back of the alts and they were magnatized. now they are not, what is my problem. any advise would be helpful.

 

[CARNAC]

Rebuilding the generators wasn't that expensive, $30-40. Not sure what else it would be but I'm sure there are others here that may provide other useful information.

 

[CCATLETT1984]

sounds like the driver's side alternator may have a bad diode in it. Pull it and have it tested, if it tests fine then there are a few wires to check.

 

[ssgtwright-usmc]

Check the ground wire from the alt to the engine block which is kinda hiding behind the alt bracket and beneith the air filter housing.
Had my alt rebuilt and still had the same problem.
After that, I traced the ground back and found it was a broken ground connection at the engine block.

 

[jbolty]

I had to replace the diode set in my left alternator. Of course the auto parts store has no listing but we found one that was meant for a generic Delco 27 SI and it seems to work fine. niehoff part # DR85R

 

[hobie237]

I was chatting with the local specialty shop that rebuilds alternators, starters, etc., sells batteries and inverters, that sort of thing. Anyway, they said the guts are the same as the civilian alternator, the only difference is the isolated ground, so they just order the rebuild parts for the civilian version and fab up the isolated ground stud. They quoted me around $100 each, though, but that was for a full rebuild, bearings, brushes, etc.

That all said, I'm not sure how driving 40-50 miles would drain the batteries on a truck with mechanical fuel injection and no ignition system, unless for some reason you were running the lights, and even then, it should only drain the first battery. So, how old are the batteries and are they in good condition? I'd get them tested.

 

[CCATLETT1984]

that is correct, the alternators internal parts are the same as the civilian ones.

 

[trooper632]

both batterys are new, had one alt rebuilt $111.00, and the ohter one checked out fine, but neither one is magnatized on the back of the bearing, and I started the truck yesterday and ran the a/c on high and left the lights on while idling and driving it. put a tester on the batteries while it was idling and the front battery showed aront 12 volts and the back battery ouput around 14 volts. Started the truck up today and drove it about 20 minutes and then noticed the seat belt light came on. after turned the truck off, it would not start low batteries, actually it turned over a little and kept trying to turn over slowly after I released the key. dont know what else to look for. I will look for the ground wire on the block.

 

[hobie237]

It was still cranking after you released the key? Sounds like the starter relay is sticking, like it was on my buddy's M1009. Are you sure the alternators are hooked up right?

 

[trooper632]

yes they are hooked up right, made sure with looking at another one, its a new startere relay. I have noticed that when the batteries get low it will crank justr for about 2 seconds before the batteries run down enough that they will not turn over the starter.

 

[CCATLETT1984]

when you have low voltage, it increases the amps, you will burn the contacts up on the starter if you keep cranking with low voltage. They may melt closed and will crank until wiring melts or the motor fries.

 

[JAsher45]

i agree you must have a bad ground wire from your alts. check you voltage output from your alts you should have 12-14.4 at one and about 24-28.5 at the other one. remember the batteries are just there to start the engine that is it... and reserve capacity

 

[ssgtwright-usmc]

For the passenger side alt, I beleive the ground is directly behind Gen-2 on top of the block in about the same location as the Gen-1 ground is located.
Did the same as you as in rebuilding the Alts and still had same problem.
I did have one bad ground behind Gen-1 so I replaced the grounds for both alts and have not had a problem since.

 

[trooper632]

found the ground for gen 1 but dont see a ground for gen 2.

 

[dependable]

above advice is good. Also check that you do not have worn or loose belt.

 

[ssgtwright-usmc]

The wiring diagram is also located in the resource tools here. I dont have the TM # right now, but you can find it for your vehicle.
The wiring diagram will be near the back of the TM

 

[CCATLETT1984]

There is no Ground for the passenger alternator. The "ground" lug comes from the positive side of the drivers alternator, and the pass alt. then adds 12v make 24v output.

 

[ssgtwright-usmc]

Look up the TM 9-2320-289-34 from the resource tab on this site.
Figure E-11 has the wiring layout for the charging system.
Do you still have it as a 12v/24volt system or has it been changed to a 12v/12v system?
Trace the negative wire back which is red with white stripe running on the side.
This wire leads into a blue fusible link wire located on the bigger stud of the engine wiring harness block.
The block is on the firewall near the glow plug relay.
May be a burnt out fusible link.
If the system has been converted to a 12v/12v system, do a google search for 24v to 12v conversion CUCV.
I beleive the website was www.roscoe.com or something like that.
If it has been changed to a 12v system make sure you starter is also 12v.
The only true thing in the CUCV is the starter and the rest is 12 volts.
My guess, bad fusible link at the engine terminal block.

 

[trooper632]

the resistor on the back of the firewall has been removed, dont know if that makes a difference or not. the wire that would normally run to the resistor from the battery and then to the glow plug relay is there. I started the cucv and removed the positive cable off the front battery and the cucv died, so i know the alts are not running the motor, i just dont know where to go from here.

 

[CCATLETT1984]

the resistor only enables the glow plugs to be operated from the slave connector when jumping the truck with both batteries dead.

you need to get your alternators checked. If they check out, then you need to see if they are making voltage while in the truck, then look for a parasitic drain somewhere in the system (draining the batts when the truck is off)