Batteries Dying in my CUCV

[jwinzlo]

Both mine and my dad's 1987 m1028's will run for a day or so on batteries, then they will completely be dead. In my experience one time, I was driving my truck down the highway about an hour and a half and just lost all juice to my radio and everything. Acts like generators aren't charging or something. My GEN 1 light constantly stays on ( don't know what that means) but my dad checked his generators and supposedly they were good. I've heard a few people have these problems and I was told come here to get pointed in the right direction.

 

[jimmy-90]

If your GEN 1 light stays on it means that your drivers side alternator is not charging or something in the 12v part of your system is a little bit shorty.

 

[davidkroberts]

Ive only had one CUCV that didnt have some sort of charging issue. If you get in the search fuction I think everything you are discribing will be covered. In fact you probably dont even need to search just read about the first thirty or so postings in the cucv forum and it will be covered most likely. Its a real common problem. From what your describing it sounds like a connection is loose or not connected somewhere but it can be anything.

The drivers side altenator charges the front battery and is replacable with an autozone stock altenator. The passenger side altenator charges the rear battery. Both altenators are 12v altenators but the passenger side alt has an isolated ground that must be used for the system to work. I would go to the CUCV forum and at the top in bold letters is a FAQ section
Cucv Wiki - Steel Soldiers::Military Vehicles Supersite

Go to the tecnical manuals and i would start with the one with the -20 on the end of it. Go to the troubleshooting section and follow the flowchart.

 

[dependable]

The #1 alt circuit is routed through heater motor speed selector resistor as well. Heater motor fuse must be good, The resistor ( the four pronged plug on firewall next to the blower motor) must be good and not grounding to body. If your alternator tests good, but your heater motor does not work at all speeds, this may be your problem.

 

[doghead]

The #1 alt circuit is routed through heater motor speed selector resistor as well. Heater motor fuse must be good, The resistor ( the four pronged plug on firewall next to the blower motor) must be good and not grounding to body. If your alternator tests good, but your heater motor does not work at all speeds, this may be your problem.

Can you show us that?

 

[captw]

charging problem

hey...thanks "dependable"...I have had an issue with the battery directly behind the headlight draining if the truck sat for awhile....once the battery is charged from a battery charger, and I reconnect the batt. terminal, I get a small spark between the post and terminal...also, in cold weather, with haedlights on and heater switch on high, if I'm driving at night, I can see a faint glow in the gen 1 lamp...I'll check out the haeter switch resistor and make sure the connections are getting good contact....W

 

[dependable]

'can you show us that?' Can't show you on that schematic, but I know the alt 1 is involved in blower circuit. On my 1st 1008, replaced the#1 alt a couple of times before I figured the heater blower was involved. Was also blowing heater fuses. Replaced blower resistor(which looked ok, but rusty terminals) and fixed my mystery alt 1 problem as well. Just now checked on a 1028, took out blower fuse, and it disabled alt 1 and light. Sorry if my post was incorrect or misleading, I wish someone could point out the circuitry on a schematic as well. What I know about these trucks is from using and repairing them, I am not a very good technition, more of an old time mechanic. Captw, Sounds like you need alt 1 diode replacement, but am no expert.

 

[doghead]

Well, lucky for me, I haven't had issues with my blower resistor or alternator( I do rebuild them as soon as I get them), so I have not tested or measured that part of the wiring.

I know the schematics are a bit hard to use since they don't show all systems together in one picture.

I would like to confirm what you said. It could be a "hidden" issue that people have a hard time diagnosing.

 

[ralbelt]

I also have a faint glow at night with the headlights on and the heater blower on high. It was the first time that I had the symptom and related it to the blower. I won't have time to chase this for a few weeks as I will be out of state. If you correct yours please post up. I would start with cleaning and dielectric grease as this is a circuit I have not done yet.

 

[mr.travo]

What would make the Gen 2 light to faintly glow? Doesn't do it while driving, just when at an idle.

 

[thedeliverator]

I've seen a faint glow from the Gen1 light at night, driving with the heater fan on full and hi-beams on. I have always assumed it was caused by a slight drop in alternator output due to the load. Everything that isn't the starting system runs off that side.

I've seen a Gen2 light come on at idle when the belt on that alternator was slipping.

 

[Warthog]

... My GEN 1 light constantly stays on ( don't know what that means) .....

It means you need to download a copy of the TM 9-2320-289-10 Operations Manuals and study what all the lights on the dash mean.

Anytime a light lights up means something is wrong or needs to be looked at.

The CUCV charging system has to have both GEN1 an GEN2 bulbs working inorder to excite the system. They come on when you turn the key to ON and should go out when the truck starts.

 

[davidkroberts]

What would make the Gen 2 light to faintly glow? Doesn't do it while driving, just when at an idle.

When at idle the Altenator doesnt engage fully. I cant remember the rpm needed for the alt to be generating but its higher than idle. When i first start mine sometimes one of the GEN lights glows for a minute until i hit the gas slightly then it stays out.

 

[dependable]

Just had yet another truck w Gen 1 problems. This one had been faintly lighting GEN 1 LIGHT w heater blower on. After repairing Alt, noticed heater blower fuse melted but not blown. This may show that those of us with the heater/Alt 1 thing should pay more attention, even if alt still charging. Anyway, could not find it in schematic, but I think I found it on truck. There are 2 brown wires coning out of back of heater fuse, one goes to heater control, the other feeds dash cluster, powering the Gen 1 light, as well as oil and 4wd lights. Hope you can make out these pictures.

 

[dependable]

Another thing I noticed today while putting it back together, the terminal pointed out in first picture is #5 on cluster plug. The other side of Gen 1 light goes to #8 on cluster plug, thinner brown wire that is shown in schematic, that goes back to [I think] brown wire that plugs into alt 1.

 

[bryancarson]

Having problems with my m1028 as well. Worked fine first year, now I’ve been chasing problems for 6 months. New belts, both alternators rebuilt by a local shop, new 925 cca batteries, upgraded the wiring to 1 gauge, still the #1 battery doesn’t charge. The only indication I have is the charging gauge is 1/16 of an inch below green. I’lll charge my batteries up and after 3-4 days she starts cranking slower. If she needs a jump I just jump the front battery and she fires right up, rear battery always reads fully charged when tested. Putting NEW Gates belts on again tomorrow (someone suggested this to me as I put value ones on ). Misery loves company so there ya go.

 

[Warthog]

You need to make sure the two pin exciter plug at GEN1 is reading correctly. The red wire should read 12v all the time. The brown wire should read 12v with the key in the run position.

Also are your GEN lights working when you start the truck?

 

[Tinstar]

Having problems with my m1028 as well. Worked fine first year, now I’ve been chasing problems for 6 months. New belts, both alternators rebuilt by a local shop, new 925 cca batteries, upgraded the wiring to 1 gauge, still the #1 battery doesn’t charge. The only indication I have is the charging gauge is 1/16 of an inch below green. I’lll charge my batteries up and after 3-4 days she starts cranking slower. If she needs a jump I just jump the front battery and she fires right up, rear battery always reads fully charged when tested. Putting NEW Gates belts on again tomorrow (someone suggested this to me as I put value ones on ). Misery loves company so there ya go.

Typing with the standard color font would be great.

The black is hard read.

 

[mr.travo]

Warthog beat me to it! That's what it sounds like to me too. The good thing is once you get this fixed you shouldn't have any charging issues! Good work!

 

[bryancarson]

So my problem was the #1 generator. After rewiring, upgrading to 1 gauge wire, new belts, testing of gen 1's leads with and without ignition on I went to Autozone and picked up the DL 7157. Since I last posted I had even replaced my printed circuit board. Oh well it works great now so going to take my original gen 1 and rebuild it myself this time and keep it as a spare.