Need electrical help!

[ashleymaree]

Hi Guys!

I realize I may be the only girl on this forum! I need you guys' help on my new truck! It's a 1987 CD3090B diesel 4x4. I got the truck figuring I'd be able to slowly learn about the engine and how it works. I love the monster! Loud, smelly, and so much muscle!

But, it's already got issues!

When I bought the truck, all the lights worked. On the way home my friend noticed the brake lights were out, and now all the lights are dead. The wipers seem to be slower, but that could just be a different truck than I'm used to.

One of the alternators rattles, but not constantly. The GEN1 light also sometimes stays on, but not always.

It looks like the black out switches/toggle has been taken out, could there be a problem here?

I know a little about the engine, but not enough to take it apart and figure this out, and all the mechanics I talk to are scared of the 24 volt system. Several have said they dont have access to the schematics for the wiring.

So, is there a place I can get these schematics? Do any of you know of mechanics in the West Michigan area that could help me? Or have any suggestions for me?

Help!


Thanks in advance!

 

[AndrewH]

The manual for the truck is on this site under the resources section I think. It would be considered a M1008, or M1028. There might be a data plate on the truck specifying which. I have poor search-fu so I don't have a link to it to post here. With the exception of the blackout lights and the blackout light switch, I believe the wiring is the same as a civilian pickup of the same year. -Andrew

 

[waayfast]

Hi, welcome!The Alt. RATTLES? HHMM?! Maybe the bearings are shot so it not charging?? Try to feel for abnormal( too much play) on the shaft of the alt. And for smoothness in rotation, both test kinda tell you the general condition of the alt. right quick. Check all the electrical connections for clean and tight.Does the truck start ok or no?? Battries full of charge or are they down? Lots of questions on top of your questions huh? Others that are more saavy with the 24v system will chime in I'm sure.Help is on the way! Oh yeah, NICE truck.

 

[NDT]

Welcome to the site Ashleymaree. All the info you will need to keep your truck running can be found here. Start with the WIKI section, found at the bottom of the list of forums. There are links to the military manuals for the truck, which contain the schematics. Also, use the seach function, using basic keywords like "CUCV lights" or "CUCV electrical". Others have had these same issues 1000's of times and have discussed the solutions here. You will need to get a good understanding of the electrical system, so you can direct the mechanics to fix your issues. My best guess of your lighting problem is fusebox issues, or loose connections resulting from the removal of your lighting switches. The alternator should not make rattle noises. Replacing that may solve your GEN light issues. Good Luck!!

 

[ashleymaree]

It's starts up awesome! no hesitation, roars to life. I will check the ALT as waayfast said to.

I have the owner's manual, it doesn't have any schematics. Will check the site here to see if I can find them.

Thanks! Keep up the suggestions!

 

[nk14zp]

Welcome to the site.

 

[AndrewH]

I think these are the manual mumbers, I'm not sure if they will link or not. from the wiki section

LO 9-2320-289-12 is the Lubrication Order
TM 9-2320-289-10 is the Operator's Manual
TM 9-2320-289-20 is the Unit Maintenance Manual
TM 9-2320-289-20P is the Unit Parts Manual
TM 9-2320-289-34 is the Intermediate Maintenance Manual
TM 9-2320-289-34P is the Intermediate Parts Manual

Search for them by TM maby....

 

[73X]

Welcome to the site. Keep us posted on your problem and how you fix it.

 

[Bob H]

Check for loose grounds and wires.
A lot of Michiganders on here. Although West Michigan is a vague description of location, there may be someone here that is close and knows something about the CUCV's.
Also check out Great Lakes MVPA (link in my sig line) next meeting is 2-21 in St Louis (Center of the Mitt)

If the 3 lever blackout switch is missing, that could part of the problem.
Those trucks are 12v & 24v both which is why it has two 12v alternators
24v for the starter and Military radio 12v for all the typical Chevy stuff.

 

[ODdave]

Not shure in where in Michigan you are but I have both manuals with all of the wire diagrams and troubleshooting charts from the drmo if you need to borrow. Hope you can figure it out w/o them as they at not the easiest to understand. Good luck.

 

[badgmc56]

Welcome Ashley. Check the brackets on the alternator that rattles. One of them may be broken or cracked and is not keeping the belt tension up to par. That would make it slip and the alternator will not charge to specs.There is a lot to learn about the electrical system. NDT has hit the nail on the head with his advise about studying the manuals. Information is power so enjoy your truck and have fun.

 

[Lifer]

Hi Guys!

I realize I may be the only girl on this forum!

Hi, and welcome to the forum! You are NOT the only girl here, either. There are a couple of wives and girlfriends who come to mind in addition to a couple of single girls who own their own trucks. When it comes to posting to the forum, Doghead's wife is probably the most active of the ladies. Never be afraid to ask questions, either, as that's how we all learn new stuff. If someone else asks a question and you know the answer, don't be bashful! If you have an opinion, voice it! If it's different from someone else's, so be it.

Having said all that, the other guys have given you a bunch of stuff to think about, so I'll keep my adice to myself (but only 'cuz they already gave it to ya).

Anyway, welcome to the forum and don't be a stranger!

By the way...nice truck!!

 

[cranetruck]

Welcome to the site!
One of the resources often overlooked is the PS Magazine section still on our old site, with lots of info, go to it and search for "cucv" or check under the "electrical" heading.
Steel Soldiers :: Military Vehicles Supersite

 

[ashleymaree]

Wow! Thanks for all the help!

I dug around in the engine compartment, couldn't find any loose wires, or grounds that weren't ... well, grounded!

My hubby helped me tighten the loose belt on one of the alternators. That seems to have stopped the rattle.

Does anyone have access to a fuse box label page? I've searched the manual, and a troubleshooting manual, can't find anything that shows what the various fuses are for. And the letters on the box itself are worn away pretty good.

The knobs for the black out system are gone. And we discovered today that the horn doesn't work either. Beginning to wonder if the taking out of the black out switches is our problem. My truck came without those knobs.

Any suggestions? can i replace the black out switches so it stops causing the truck to "black out" on its own?

Thank you again for all the help!!!!

Ashley

 

[NDT]

I did some searching and no I can't find the fuse box layout either. I will assume you found the wiring diagrams in appendix F of the -20 manual. You can sort of figure out which fuses are for the lighting circuits. For sure you can put your lighting switches back to stock, the switches and the little panel come up on Ebay from time to time. To aid with troubleshooting your issue, buy one of those "test lights" from an auto parts store, and poke around in the fuse box, checking both sides of the fuses when things are working and then when not. Corrosion on the fuse clips and loose fuse clips can cause intermittant issues like you are having.

 

[AndrewH]

Can anyone verify if the m1008 uses the same fuse block as the civilian trucks? I have the '86 factory manual set for the civvy models. Has a decent diagram in it. I will try to scan it.....-Andrew

 

[Goose2448]

Welcome to SS. I would go to Autozone and buy the repair manual for a Chevy Truck form 73-87. There will be some differences but most of the electrial and trans on back stuff will be the same.

 

[ODdave]

the fuse block is the same as civi. the wire harness is the same as civi it just has an additinal harness piggybacked on to it for the mill spec. GM did use mulltiple differnt harnesses for differnt insturment clusters and engine combos, this is where the hard part is. i removed my harness and stripped all of the mil spec from it for use of 12V with my cummins. pretty easy to do as long as you take you time.

 

[NDT]

I found the fuse box layout, search for the "CUCV FAQ" thread. It is there.