CUCV electrical problem, no head lights

[dieselcrawler]

I seem to have a problem with my head lights on my '84 CUCV 1028 military truck. I have no headlights, no running lights, no dash lights, no reverse lights, and no turn signals. There seems to be voltage in all the right places up to the junction block that goes thru the fire wall, but I seem to lose it after that. I don't know for sure which fuse they should be on, (all fuses are good) but there are 2 or 3 that never have power on them, with the key on, off, or acc. Can anyone help? (this is really sad, because an electrical problem has me, an electrician, stumped. Houses I can work on, cars and truck electrical sys are a diffrent story!)
Merry Christmas to all... and to all a good night...
Greg

[britannic]

Did you engage the blackout relay by setting the service lights to off at all? What you describe is the behavior I see on my CUCV when I flip the right hand "Service Lights" switch to the middle.

[dieselcrawler]

Thanks for the quick reply... yes, it is possible, now that I think about it, that I hit the switch. Can you tell me where it should be set for normal operation? Mine is missing the labels, and both switches seem to have 2 or 3 positions. Thanks...
Greg

[dieselcrawler]

I just ran outside to check, and that was the problem. Put the right side switch to the "up" position, and what do you know, the headlights came back on. I had my gage cover off today, and must have bumped the sw, and didn't know it... Don't know why I never thought of it...
Thanks...
Greg

[britannic]

Click the lefthand "Blackout Drive Light" switch all the way to the bottom and the righthand "Service Lights" switch to the top.

To enable the Blackout setting, set the lefthand "Blackout Drive Light" all the way to the top (it will spring back, but still toggle) and the righthand "Service Lights" switch to the bottom. If the righthand "Service Lights" switch is in the middle, it switches off the service lights, but won't activate the Blackout lamp if the rh switch is off.

[dieselcrawler]

I know some will cring when I say this, but this is just one more reason to de-miltarize the ol' 'crawler. The blackout lights have all been removed/disconnected, and all that seems to be left are the switches, and headaches when one get's fliped.
There isn't really any value in keeping things orig, as things have been messed with alot, I think I may rewire the whole thing at some point. I plan to keep the 24v starter, but make 2 compleat 12v systems out of it... one will just have to be compleatly isolated, as in, 2 wires ran to everything.
Thanks for your help...
Greg

[britannic]

Apart from the starter and the feed to the resistor bank, the truck is wired for 12v. The alternators used insulated grounds so they can be switched into series to generate 24v, otherwise they will happily generate 12v.

If you don't already have the military manuals in .pdf form, download them so you can check the current wiring set up to plan your conversion.

Here's a link you can check out for the docs: http://www.hmmwv.org/HMMWV/pubs.htm

[dieselcrawler]

I'll check on the prints from the mil web site... tryed to open them just now, but something doesn't want to work, cant get them to down load. I'll mess with it more later tonight, getting ready to head to the parent's house for Christmas dinner.
However, I plan to eliminate most of the mil wiring harness, useing a stock civvy harness under the dash, and re-do what's left under the hood. It's really mostly simple, if I set things up the way I have mind, and I should be able to keep my 24v starter. Simple is best, I plan to tear into that when it gets a little warmer.
Take care all, enjoy the holiday... Merry Christmas!
Greg

[Peter J. Bierman]

I did de millitairize my truck.
Took out one generator, and the resistor bank for the glow system.
Use a serial/paralel relais to put battaries in series to start with the 24V starter.
jumped the blackout switch for normal operation off the lighting system.
One generator is capaple off charging both battaries.

there is a pretty good write up at the folowing link, but they go to a 12V starter, but is might help you to start.

http://www.roscommonequipmentcenter.com/news_notes/nn10.pdf

Good luck Peter

[dieselcrawler]

Hope everyone had a great Christmas...

Ok, here's the plan... I want to keep both alternators, and both batterys. I'm going to have 2- 12 volt systems, one that will be grounded like any other vehicle, and one that is isolated compleatly. I will have to run a insulated ground to any item that I would power with the 2nd system. My plans are to run aux off road lights, as they have taxed the stock electrical system on other trucks that I have used them on.
To do this, I will have to rewire the stock wiring harness under the hood, and may ditch the one under the dash all together, if a civilian truck harness will match up with no problems. It will as far as I know, I just don't have one that is from a diesel, tho I think that it won't make any diffrence. As long as all my lights work, and the truck runs right, it's all good... **grin**
I do need this question answered tho... I plan to gut the wiring under the hood... I know the pink wire goes to the IP solinode, but how is the high idle solinode controled? I assume that there is a temp sending unit that tells 'something' when to turn this solinode off, so the idle speed drops, but how does this work? What wires go where? I have had no luck being able to find/download wiring diagrams for this truck, dispite some sugjested links from fine people like our friend Britannic. (Thanks for the input, but I just can't get it to work... don't know if it's me or the computer, or both!) I want to simplify the system as much as posible, no auto glow plugs, just the basics. What is the bottom line, what all can go, and how little do I need to have the motor run right? The rest I can figure out, heater motor, wipers, dash lights, etc. But I will be installing mechanical temp gage, dual amp-meters, and keeping my 24v starter.
Thanks for the input,
Greg

[britannic]

Originally posted by DieselCrawler:
Hope everyone had a great Christmas...

Ok, here's the plan... I want to keep both alternators, and both batterys. I'm going to have 2- 12 volt systems, one that will be grounded like any other vehicle, and one that is isolated compleatly. I will have to run a insulated ground to any item that I would power with the 2nd system. My plans are to run aux off road lights, as they have taxed the stock electrical system on other trucks that I have used them on.
To do this, I will have to rewire the stock wiring harness under the hood, and may ditch the one under the dash all together, if a civilian truck harness will match up with no problems. It will as far as I know, I just don't have one that is from a diesel, tho I think that it won't make any diffrence. As long as all my lights work, and the truck runs right, it's all good... **grin**
I do need this question answered tho... I plan to gut the wiring under the hood... I know the pink wire goes to the IP solinode, but how is the high idle solinode controled? I assume that there is a temp sending unit that tells 'something' when to turn this solinode off, so the idle speed drops, but how does this work? What wires go where? I have had no luck being able to find/download wiring diagrams for this truck, dispite some sugjested links from fine people like our friend Britannic. (Thanks for the input, but I just can't get it to work... don't know if it's me or the computer, or both!) I want to simplify the system as much as posible, no auto glow plugs, just the basics. What is the bottom line, what all can go, and how little do I need to have the motor run right? The rest I can figure out, heater motor, wipers, dash lights, etc. But I will be installing mechanical temp gage, dual amp-meters, and keeping my 24v starter.
Thanks for the input,
Greg Greg: If your email can handle large files, I could email the manuals.

BTW: do you have Acrobat Reader installed - it's the format the manuals are in?

[dieselcrawler]

Britannic,

I was able to download some of them... let me check to see if wiring diagrams are part of what I have. If not, I'll let you know, and we can try to email them then. Do you have just the wiring diagrams, or is it all together in one package?

By the way, I still seem to be having problems, just not with the lights, per say. More of a charging issue. I've had both alternators tested, both should be ok, but still am draining the batterys. I'm gonna rewire some of it today, and see if that helps. After driving home last night with my lights getting steadily dimmer, I have to do something... I'll let you know how it goes.

Greg

[ueckebes]

d crawler /brit i have also had this problem with my 86 milt blazer but my sudden loss of all lights is for some reason resulting from a single fuse in the fuse block ,it dosent blow them 20/30 amp it just on one ocassion slightly melt one and now the fuse is replaced but fits poorley some times it just needs a little touch to get things working .also batteries no matter the brand seem to last long , about a year none of my other 6.2,s have give me this trouble.i totaly love the blazer but dont care for the 24 volt crap im thinking of a 12 volt conversion also,may need some help please .

[Peter J. Bierman]

I did have a problem sort a like that,
turned out one generator was sort circuiting tho individualy they tested ok.....
Was the main reason to go to one generator setup.
( the twin turbo set up and the airco wouls have forced me to anyway )
I figgured that the simpelest way was the series/paralel relay to go to 12V and keep the heavy 24V starter.
The battaries are now more evenly loaded too.
Works fine for me.

Peter

[dieselcrawler]

Hey all...

As I said, I had both alternators tested last week, and both tested ok... however, plain and simple, they just wern't working. So I took them apart, and found, aside from some mud, (gee, I wonder how THAT got there???) that the brushes and the slip rings that they ride on were very dirty. I cleaned the brushes and slip rings, made sure all connections inside were tight, and put 'em back on the truck. Pumpin' out a nice 15 volts now... at idle! And the amp meter is now showin' that at least one battery is takin' a charge, even with lights/fan motor/etc turned on. I hope to install a 2nd amp meter to monitor the right side alt/rear battery situation as well. As I tinker with it more and more, I am slowly comin' up with a plan for the rewire project...

I also want to mention that I have had a problem with the partialy melted fuse myself. Not the very bottom one, but the one on the far right of the bottom full row. When I first got the truck, the lights would just go out, and if you kicked somewhere under the dash (as they would do this while driving!) they would come back on. I'm guessing that it was this melted fuse, it has since been replaced, and has caused no further problems. I was able to pry the fuse holder tabs a little with a small screw driver to make them hold tighter. Seems to have worked.

Greg

[britannic]

15V is a bit too high for charging the batteries, unless this truck is a CUCV with the original 14/28V set up, which means it's fine :D .

[dieselcrawler]

I never get over 15v/29v at idle, drops when a load is added... is this too much for normal batterys? Will it cause a shorter life, maybe such as was sugjested by an earlier post from someone else (didn't catch the name... sorry!)?

Greg

[britannic]

Originally posted by DieselCrawler:
I never get over 15v/29v at idle, drops when a load is added... is this too much for normal batterys? Will it cause a shorter life, maybe such as was sugjested by an earlier post from someone else (didn't catch the name... sorry!)?

Greg These voltages are healthy for the CUCV with the military wiring set up.

[dieselcrawler]

Here's the latest on this project... I've managed to find the orig charging problem. I'm sure that cleaning up the brushes and slip rings in both alternators helped, but I found a bad voltage regulator in the alt that supplies the 12volt system. I replaced it with one out of another alt I had, seems to work great now.
In the process of narrowing it down to this, I have rewired the alternators so that each directly feeds each battery, and each is monitored by it's own amp meter. I have also moved my aux lights to the 2nd alt, as the are isolated from the ground of the 1st system. I beleive this will work well now.
Peter, I would be interested to know how you wired your truck, you mentioned relays and such to charge both batterys, yet keep the 24v starter. I have a plan of my own to do this, just wondering if it's similar to yours... and the fact that I'm always open to new ideas. I've thought of a installing a cross-over system to allow eaither alt to cross with the other for charging, so if one goes bad, you can still charge all batterys, but still have 2 compleat, isolated systems. I'll have to see what I come up with, and if it's worth the trouble.
Till next time,
Greg

[Peter J. Bierman]

I am not sure but in basics; :rolleyes:

I took out the left hand side generator with as much wireing I could find.
Put in a series/parallel relay for the starter and hooked it up as in the diagram on the side of off the relay.
What this relay does is connecting the 4 battary cables so that the batt's are parallel meaning the positive by the positive and the negative by the negative. Negative is switched to ground.
The normal truck circuit has a special 12V connection on the relay ( this stays 12V all the time )
On the relay is a 12V 50 connection on whitch you plug in the starter activation circuit (from the start switch )And a 24v 50 to the bendix.
What happens if you put the switch in start is that the relay puts the battaries in series ( one neg to one pos and one neg to ground one pos to the starter( creating 24V ) and 24V on the bendix solenoid on the starter.
The solenoid kicks in and the starter spins on 24V, wile the truck cicuit is still fed by 12V.
The charging wire from the generator is on one of the pos connections on the relay.
As soon as you let go the starter switch the batt's are switched back the pos by pos and neg by neg.

It all sounds pretty complicating but it is not.
On the relay is a diagram, just hook it up step by step and it is a piece off cake.

The beauty off it all is you keep your strong 24V starter and only need one generator. smile.gif

Oh :eek: , I forgot, you have to remove the resitor bank from the glow system, it works on normal 12V now like it was ment to be.

I can figure out details like wire colours if you want but see what you think of this setup first.

;) Peter

[dieselcrawler]

Not to worry about wire colors, I should be able to figure it out... I've been told I'm an electrician **grin** The resistor bank is already gone, it didn't work when I got the truck. I have already installed an old starter solinode from a Jeep to isolate the 2 batterys... I think I'm going to keep both alt's as long as both are working... seem to be doing great now. All I have to do is kick in the solinode to tie the 2 bat's together for use of the starter, otherwise, I keep them sepirate, so one doen't drain the other, and so I can keep tabs on each one's amp meter. I plan to come up with some sort of relay set up to alow eather alt to charge eather bat, or both... have to think about it, but now that they are working, it may be a while! I'll keep ya posted. Thanks!

Greg

[jboone47]

I have a similar problem with my '84 M1008 CUCV and hopefully, some of you with electrical problems can help.
Turn on headlight switch and fuel gauge drops to zero, turn signal indicators light up and red seat belt light comes on. Turn signals still work, but indicators stay lit. Headlights/dimmer work OK.
Turn off headlights and fuel gauge returns to normal, as do turn signals.
I've replaced: Headlight switch, ignition switch on steering column, and starter relay, but problem persists.
Must be a short somewhere, but I'm stumped. Am now considering replacement of the main wire harness under the dash.
Any suggestions appreciated.

1984 6.2 M1008
1986 6.2 M1009 Blazer

[dieselcrawler]

I don't know much, but I've seen/heard of simular problems and it's turned out to be a bad ground... check that, make sure any place you have a black wire screwed/attached to sheet metal is good and tight, and makin' a good connection. It may even be the connection for the ground to the inst. panel it's self.

Are the light that do come on when you turn your head lights on 'full brightness', or just kinda dim and glowing? If they are about 'half dim' you very well may have a ground problem.

Good luck...

Greg

[jboone47]

Greg:
The lights come on full bright, not dim, that's what's so confounding about the problem.
I'm stumped.
Thanks for reminding me to check the grounds again.
Joe

[dieselcrawler]

Joe:

Have you checked the connection to the gage cluster itself? If you haven't/arn't farmiliar with it, there's a multi-pin connector that goes in the back, near the middle left. You might try to disconnect/reconnect it, and see if that helps. It sounds to me like all of your problems are in the gages, right? Every thing that goes to them, goes thru that connector. If you do have a problem with the gages themselves, you can replace them with a cluster from any late 70's to mid 80's truck of the same body style. The plastic body should be ok, the "wiring" for the gages are part of a plastic 'film' that is attached to the back of the gage body, and I have a few of thoes from these trucks, if that proves to be the problem I'd be happy to let you have one. Keep your progress posted... good luck.

Greg

[britannic]

Originally posted by DieselCrawler:
Joe:

Have you checked the connection to the gage cluster itself? If you haven't/arn't farmiliar with it, there's a multi-pin connector that goes in the back, near the middle left. You might try to disconnect/reconnect it, and see if that helps. It sounds to me like all of your problems are in the gages, right? Every thing that goes to them, goes thru that connector. If you do have a problem with the gages themselves, you can replace them with a cluster from any late 70's to mid 80's truck of the same body style. The plastic body should be ok, the "wiring" for the gages are part of a plastic 'film' that is attached to the back of the gage body, and I have a few of thoes from these trucks, if that proves to be the problem I'd be happy to let you have one. Keep your progress posted... good luck.

Greg FYI on the replacement gauge clusters, different years and models have many variations on the plug wiring, so be prepared to remap/reposition the contacts to match the existing cluster.

[jboone47]

Greg:
You're right, the problem involves the gauges (fuel, seat belt) and turn signal indicators.
I wondered about the gauge wiring "film" behind the cluster, but haven't removed it yet. I'll try the multi-pin connector.
Thanks for the tip.
Joe

[jboone47]

Greg: Looks like the harness on the back of the cluster may be the problem. You said you had several - do you have one for a 1984 M1008?
I didn't see your e-mail address to contact you.
Thanks,
Joe

[dieselcrawler]

I'll have to check what I have... the problem may be as was stated earlier, that the ones I have may not be the ones you need, they might have changed from year to year, and with diffrent options, as mine are from civilian trucks. The main part of the cluster, as in, the fuel gage and speedo should be the same. the others, the gages on the left side, for the alt's and others, is where I expect the diffrence to be.
Do you have yours off of the truck yet/now? I think the easiest way to make sure we have the same one is going to be to remove the film from yours, photo copy it, as long as it's possible to see the "lay out" of it, and send me that. I will compair it to the ones I have, and if one matches up, I'll send it to you. another option might be a digital photo. A third might be for me to just pull the gages out of my own, (a M1028) I would expect it to be the same, and could compair them that way.
At any rate, you can email me at electricwonder at hotmail dot com.
Good luck,
Greg

[84 Convert]

That dash/headlight problem sounds all too familiar! I have the same problem in my CC. The only difference is that when I turn the wipers on (on the stalk) they don't work and the blinker indicators will light up! With mine I think there might be a problem with the high beam switch on the column because there seems to be alot of wiring through there, and the headlights and blinkers are part of it. If you do solve your problem though, let me know.

Gregg

[jboone47]

Gregg (84 Convert):
That's precisely the problem I'm having with my M1008. I've replaced the light switch, ignition switch, starter relay, etc., to no avail. I'm going to replace the "film" wire harness on the back of the instrument cluster next. If you solve the problem in the meantime, please let me know, because that will also solve mine.
Thanks,
Joe

1993 K2500 6.5 TD
1986 M1009 6.2
1984 M1008 6.2
1987 M998 HMMWV 6.2

[jboone47]

To DieselCrawler and 84 Convert:
I found the problem! Nothing wrong with the gauge wiring harness film attached to the back of the cluster, or any switches either. There is a single, black ground wire coming out of the main harness behind the instrument cluster. This wire is grounded to a terminal attached to the parking brake assembly. It was broken. Reattached the wire and it fixed everything. Wipers, fuel gauge, voltmeter, and turn signals all work properly.
Thanks for all the suggestions.
Joe :D