m1009 Electrical Hell

[cowboyb06]

Alright. I've tried my best using the manuals/stickys to try and track down what exactly is causing my problems, but to no avail. I put two new alternators and two new batteries in, and I still can't seem to hold a charge. IE parked the truck friday, came out monday morning to start it up and my batteries were completely dead.

When I turn the truck on before i crank it I get a GEN 1 light but nothing from the GEN 2. i've checked the fuses so I believe that is caused by a burned out bulb in that slot. She'll hold a pretty good charge when I've driving, but after I park it, even for just a couple hours my batteries have dropped. Anyone have a schematic for the wiring on it or know what a common parasytic drain might be? I'm damn tired of having to take the batteries out at night to charge them.

 

[Bobert]

RE: m1009 Electrical heck

I had similar problems, I would recommend getting a cutoff switch so you don't drain them all the time.

Before I crank, I don't get a gen 2 light, sometimes I get more lights than other times. But it works so I don't mind.

Do your lights all work? A common grounding place is under the front battery tray.

Yours sounds like a pretty big drain.

 

[cowboyb06]

RE: m1009 Electrical heck

Thanks for the quick reply.
yeah: headlights, taillights, blinkers, hazards, running lights all work. When you say cut off are you meaning to keep any flow from going out of the batteries? I'm fixin to get off work and have a day off tomorrow so I want to try and finally get this all sorted out.

Is it possible it could be something from the BUSS BAR or the plug on the front for auxilary components thats pulling it down?

 

[Michael]

RE: m1009 Electrical heck

CUCV charging problems. You have done a search and read all of the previous threads haven't you? Are you getting 14.* volts at each battery? Are both batteries going dead or just one? The schematic for the wiring is in the -20 and -30 in the appendix. Some trucks will go dead if you leave the blackout light/regular light switch on.

You could undo the ground and hook up a test light to check for a voltage leak. If the light glows there is one. Then unplug one fuse at a time to narrow done which circuit it is on. If that doesn't find it start unhooking things that aren't fused.

 

[ida34]

RE: m1009 Electrical heck

When you say you replaced the alts, did you put in isolated ground alternators or just some replacements from the parts store.

 

[cowboyb06]

RE: m1009 Electrical heck

Its usually just the rear battery thats not charging/going dead. I've searched through-out alot of the previous threads, but I'm still kinda new to the site. What exactly are the -20, -30? I've got the manuals for the m1009 downloaded but I don't know what y'all are referring to.

To address the alts, they were the closest i could find. same mounts, almost the same connections. They're off a 3/4ton 1980 chevy. I don't know if thats part of the problem or what. I can work on my old jeep no problem but this two batt diesel is confusing the crap out of me.

 

[CCATLETT1984]

RE: m1009 Electrical heck

the -10 is the operators manual
the -20 is the unit manual
the -30 is the direct support manual

Cowboy, you have the wrong alternators, the alternators on the CUCV are special. They have the ground lug isolated from the rest of the case, I'm suprised you didnt get a fireworks show when you tried to hook them up.

Do you still have your old alternators, any good shop can rebuild them?

 

[cowboyb06]

RE: m1009 Electrical heck

yeah I still have the cores. So If I get them rebuilt it'll take care of the charging problem I'd assume. But that wouldn't solve the drain problem would it?

Without even starting it, I can take my batts fresh off the charger, hook them into the truck, leave it for a couple of days, come back and its completely drained.

 

[CCATLETT1984]

RE: m1009 Electrical heck

well, i bet you have a fusible link burt out now, but yes that is the root of your issue.

not having the isolated ground lug, one or more of the diodes in each alternator are probably burned out, and that would cause your drain.

For reference I paid $125 a piece to have mine completely rebuild about 2years ago.

Also while you have the charging system apart, pull the batteries and have them load tested, to be sure you dont have an internal short or weak cell. That can be done at any auto place.

 

[JohnFire]

RE: m1009 Electrical heck

Disconnect the batteries from the power block, connect a test meter to read amps. That will tell you if you have a draw off the 24V side. Do the same off the first battery. That one you can do it between the connector and the battery itself. Again this will tell you if it is the 12V side. I am sure others on here can explain better than myself.

 

[cowboyb06]

RE: m1009 Electrical heck

awesome. I figured that might be the case, being a college student I'm not exactly able to drop as much money as I'd like on it. I know theres a place up in Gainesville, Tx, that does a good job rebuilding them. I think he quoted me between 50-150 a pop, depending on what all needs to be replaced.

Thanks for all the help. Anything else I should know?

 

[CCATLETT1984]

RE: m1009 Electrical heck

just be very clear that they must have the ground lug isolated from the case.

 

[cowboyb06]

RE: m1009 Electrical heck

Will do. I guess in hindsight thats why some of the connections for the stock(read military) alternators didn't have a place to hook up on the civy ones i got.

And in response to the LIGHT SHOW. . .
When I tried hooking up what I thought went onto the civy alts when i got them, I got quite a spark over by the drivers side alt relay. Reminded me of getting an arc going on a welder.

 

[badgmc56]

RE: m1009 Electrical heck

Disconnect the battery (hot leads) from the alternators and see if the batterys are discharged after sitting a couple days. That will eliminate alternator drain. Have had this happen quite a few times over the years. You can also remove fuses one at a time and check for voltage draw at the batterys.

 

[cowboyb06]

Re: RE: m1009 Electrical heck

You can also remove fuses one at a time and check for voltage draw at the batterys.

from the front or rear battery?

 

[Michael]

RE: m1009 Electrical heck

Putting in an unisolated ground alternator means you hooked the front battery up to a dead short. Something in the wiring harness had to give, probably the fuseable link. You will have to fix that as well as replace the alternators. Actually, once you understand the system, you can get by with only one isolated ground alternator because one of them does ground to the frame.

 

[Michael]

RE: m1009 Electrical heck

It depends on the fuse. The 12 volt circuits would be draining the front battery and the 24 volt circuits would be draining both. There are both 12 and 24 volt circuits fused in the fuse block. I would look for were you burned your wiring harness up and fix that first. I bet that is were your problem is.

 

[cowboyb06]

RE: m1009 Electrical heck

right on. SO- loosing charge on battery because I have an unisolated ground alternator which in tandem with a blown fusible link would allow my truck to run and lights function normally but not charge the batteries. replace said fusible link, have OEM alternators rebuilt and I should be eatin' high on the hog?

 

[cowboyb06]

RE: m1009 Electrical heck

also what Amperage fusible links do I need?

 

[CCATLETT1984]

RE: m1009 Electrical heck

i forget what size the links are, but I think they are rated by wire ga., the ones that i got are orange and were from the local autozone, they've held up just fine.

The links you are looking for should be in a group of about 4 just below the glow plug relay on the firewall, they may be taped up, but thats where they will be.