Charging system help????

I have a 1010 that was converted to a regular cucv setup by uncle sam. I noticed the driver side alternator is only running 12.3vdc when running, and the gen 1 light does not come on. the passenger side alt. is putting out 14.6 when running. I figured it was a bad alternator so I switched them and have the same result. I have checked all of the fusible links and none are burned out. Now that the front battery is getting drained the gen 2 light comes on but not the gen 1 light. Is this because the 24vdc is low so it thinks the gen 2 is bad? Or is it possible the conversion to alts. is fubared? Thanks for the help.

Matt

Where are you taking your voltage readings from? Could be high resistance in the circuit if you're measuring voltage at the battery. Try measuring the voltage at the output stud on the back of the generator. If you're already doing that then i'm puzzled as to why the left is 12.3 Volts.

It is the same at the battery and the output stud. Both alternators have 12 volts on the little red wire between their respective ground, and both alts have the same voltage on their output studs when the engine is off. The only time things are different is when the truck is started, gen 1 stays the same and gen 2 goes to 14 volts.

Matt

And this occurs whichever generator is in the #1 (driver side) position? Check the ground wire, it may be corroded where its connected to the motor. Remove it and the stud, clean the connection very well and reconnect it, then see if anything changes.

Ive used jumper cables straight to the battery to bypass the ground. I am going to pull both alts. and have them tested just to rule them out.

Matt

Replace the bulb for the gen1 light in the dash, if its burned out the alternator will not charge.

Was that by design or was it a "hey, look what doesn't happen when I remove the bulb"?

I wish it was something as easy as the bulb. It comes on until startup then shuts off like gen 2.

Matt

@ 319
It was by design, so if the bulb burned out you would have it replaced and be notified if the generator failed.

@ uscgmatt
The only thing i can think of is the the alternator is not being "excited" into making current. But if the light comes on, the circuit is working. Have that alt. checked (could be a bum regulator). If its not the alternator, wiring fun will commence.

Check the fuses under the dash. They are not necessarily labeled correctly so check them all.

Your gen 1 light should be on very dim and get alittle brighter if you turn on the headlamps.
Check voltage at the big main wire from each alt.
You should show after startup around 14 volts at gen1 D side
And 24 to 28 at gen2 P side.
I am not sure the Alts are interchangable.
I think there is something different about Gen2

underdog said:

Your gen 1 light should be on very dim and get alittle brighter if you turn on the headlamps.
Check voltage at the big main wire from each alt.
You should show after startup around 14 volts at gen1 D side
And 24 to 28 at gen2 P side.
I am not sure the Alts are interchangable.
I think there is something different about Gen2

Click to expand...

As long as you have two ORIGINAL MILITARY alt's they are interchangable. GEN2 MUST (READ ABSOLUTELY MUST!!!!) have an isolated ground.

I finally had time to get back to the truck. I found that both of the plastic plugs that plug in to the top of the alts were bad. I replaced them with insulated spade connectors and 14.7 volts on each battery.

great, glad to hear you got it fixed.

uscgmatt said:

I finally had time to get back to the truck. I found that both of the plastic plugs that plug in to the top of the alts were bad. I replaced them with insulated spade connectors and 14.7 volts on each battery.

Click to expand...

I thinks i'm having the same problem as you, except the gen 1 light never came on. The gen 2 light only comes on. The problem is it's been that way ever since i bought it. So there should be no reason why it's crappin out on me now right? Well i guess i should blame myself cause i ignored the problem untill my battery all the way at the front of the hood kept draining. If anyone knows anything....PLEASE HELP ME OUT!!!!!!!!!!!!! thanks

except the gen 1 light never came on. The gen 2 light only comes on.

Click to expand...

My gwn 1 light also never came on when the truck was running. I replaced both plugs on the alts. and the belts. now it works great. Hopefully this helps.

matt

uscgmatt said:

My gwn 1 light also never came on when the truck was running. I replaced both plugs on the alts. and the belts. now it works great. Hopefully this helps.

matt

Click to expand...

Update on the alt. I have fixed it and i'm well on my way to driving it again. Thanks for the help.

needing some help with My cucv M1009?

I just bought a cucv m1009, from a guy that had no idea what it was or anything about it. Im happy with the buy, and its a very low millage unit, ( 43K) very clean as well, it has some bugs and Im working them out.

I have been going over it and am unsure of a few things... perhaps some one can help, when driving it home with 2 brand new batteries the gen 1 light was off and the gen 2 light was on. I tested the drivers side alt, and found 14.3 vdc, and the pass alt had 25.2vdc, so I figured all was well, both batteries were fully charged.

none of the lights worked after turning the service light switch on, and I found that the fuse terminal was loose and not making contact with the fuse, so this evening when doing a oil change and fuel filter change as well as other fluids, I repaired the fuse terminal, fired it up and all is well, gen1 light off and gen 2 light on? took it for a test drive and gen 1 light came on, and gen2 light came on.... this is where Im confused, I measured voltage at the batteries and got 27.7vdc, then measured it at the alts, and got about the same, so after looking at some threads and info and some rather poor schematics on the net, it would appear that the lights on mean all is well, or does it? they are very bright so does this indicate a problem or all is working?

I have a strong back ground in vehicles and am a Mechanical engineer. I own a engineering and fabrication business that builds, preps and designs off road race trucks and dirt toys, I have been looking over this site and am very impressed with whats on it.. Keep up the good work and thanks for having a wonderful site.

First off Welcome to SteelSoldiers and MV ownership.

Second, this tread is a couple of years old and covers the M1010 CUCV. It is a totally different animal than your M1009 CUCV. Look elsewhere for answers.

You need to visit the CUCV Forum and read the following:

At the top of the page is the CUCV Wiki
Cucv Wiki - Steel Soldiers::Military Vehicles Supersite

It has alot of infomation and links to all the CUCV Tech Manuals. You will find the wiring diagrams in the Appendix of the -20 and -34 manual.

And then read the FAQ Thread
http://www.steelsoldiers.com/cucv/20600-faq-thread-cucvs.html

It has alot of info about parts, trick, tips, etc......and alot of junk....

Now to your questions.

The Idiot light for the alternators MUST be in place and working for the alternators to work. If they are lit up then the alternators are not charging properly.

In a stock system, each alternator, when functioning, will put out ~14.5v.

When GM designed the alternators, they modified the 27SI, type 100 alternator ('80s Cadillac) to have the internal electricals to NOT use the case as a ground. They instead "isolated" the internals with insulators and added a "ground post". This allowed them to take the 14v from the drivers side alternator, feed it to the passenger side "ground terminal" and have 28v at the passenger side positive terminal. The alternator is only generating and additional 14v but combines it for 28v. Sounds confussing but is really a very simple(ingenious) design.

These trucks have lead a very harsh life. The electrical contacts have corroded and dirt/gunk built up over the 25+ years. By cleaning the fuse block, ground connections, etc. 95+% of all electrical issues can be solved. You should also remove the instrument cluster and clean the contacts and check all the bulbs.

When I an working on an electrical issue I will cut and paste the particular wiring diagram and "color" the wires that I am tracing. It makes it very simple to "see" the circuit.

Also look at the first few pages of the Troubleshooting Section of the -20 or -34 manuals. It covers how GM designed the wiring diagrams and what the wire numbers represent.

Good luck and God Speed.

Thanks.

Thank your for your help, its is much appreciated.
the thing I can not under stand is that it appears to be charging, with any ware from 27 to 28 volts at the alts and batts. so perhaps its a simple connection causing the lights and the alts are working fine...

I'll remove all the wires and test and give them a good cleaning, perhaps that will solve all my woes.. thanks for the link to the TM's

I'll keep you posted on what I find, again thanks, and this truly is a great site.