gen 1 light not coming on.

[DIESELGREEN]

Ok, checked all the basics and researched back thru threads pertaining to gen 1 problems, but here goes... As of late, over the last month or so, I've been noticing my lights getting dimmer at night, and also my volt gauge is reading on the "high" side of the yellow area, used to be right in the middle of the green. finally, while I was doing other repairs today, she wouldn't start. once running again, tested both batteries, 12.40v rear and 11.5x front. gen 2, reads 26.xx volts and gen 1 (driver's side, hope I have the numbers right) is putting out about 11.5v. (close to reading of front battery. here's the other thing.. My gen 1 light has not been coming on. both are supposed to cycle/illuminate at key-on and startup, right? I replaced the bulb in gen1 spot and cleaned the contacts, no dice. I believe my #1 alternator has failed. will this make the gen1 light not work??? thanks in advance. P.S. batteries are both only 3 months old.

 

[68impalass]

check your heater fuse and fuse contacts

 

[Iceman3005]

Both gen. are supposed to put out 14.5v each. Sounds like your gen's. are failing.

 

[Wagner]

You might try checking the new bulb in the Gen 2 light socket just to make sure there is continuity through the new bulb and the bulb holder. Also you might try spraying some electronic contact cleaner around the area where the Gen 1 bulb plugs in to make sure you are getting a solid clean contact with the film that conducts the power to and through the light.

My Gen 1 light was acting up intermittently and it took several tries to getting to work properly. The film that the power circuits are on gets weak and brittle with age and the some of the instrument lights can work or not any given day. As you probably know if the Gen 1 light is not working properly then Alternator 1 will not work as it cannot draw the power need to excite the alternator.

 

[Warthog]

The design of the CUCV has the GEN lights as part of the chaarging circuit. The light doesn't work, the GEN won't work.

GEN1 excitor circuit uses the heater fuse for it's power. Check the Heater fuse as stated above.

Have you ever cleaned all the fuses and fuse box since you got the truck?

 

[DIESELGREEN]

I have throroughly cleaned all of them. I've had the dash apart and replaced every one of the bulbs, cleaned the twist-in sockets with contact cleaner, and cleaned the contact points of the sockets and the contact areas of the printed circuit on the back of the cluster with a fiberglass spot sanding pen (works EXCELLENT on cleaning electrical parts). The heater works great at all speeds. I even replaced the gen1 bulb a second time and tried swapping it with the gen2 bulb to eliminate any possible cause of malfunction of the bulb itself....nothing. the printed circuit is fine. I don't believe any power is GETTING to that bulb. All connections secure at the alternator and wiring ok. I understand that bulb is part of the exciter circuit and will not charge without it. Correct if i'm wrong, but the GEN1 bulb IS supposed to illuminate at key-on, right?

 

[Warthog]

Pull the two wire plug on the driver side alternator. Check for voltage on each wire.

12v on the red wire at all times
12v on the brown wire with the key on, zero v with the key off.

If you have these readings, the inside wiring (and bulb) is good and you need to check the alternator itself.

 

[jdnodo]

My gen 2 light is doing the same Iv checked the output of th alt everything is good iv changed bulbs i cant get the stupid light to work anyway to bypass the light to get the alt to charge. What fuse on the fuse panel does gen2 light run off of

 

[Smokingman]

Run a new ground(with out removing the old one)from the drivers alternator to the frame(8 gauge wire,ends,and a self tapping screw).Run a new one from the negative on the front battery to the frame as well.This solved my alternator issues.

 

[nthompson2110]

Similar Trouble

I've been having the same trouble with my Gen 1 light and today i lost all exterior lights and instrument lighting. my lights for Gen 2, wait, WIF, and the sort still work but i have no blown fuses that I've seen and I'm now at a loss. Usually I don't feel this dumb but it's one thing after another here. Anyone have any ideas? I did some searches but probably didn't word them right.

 

[Warthog]

I've been having the same trouble with my Gen 1 light and today i lost all exterior lights and instrument lighting. my lights for Gen 2, wait, WIF, and the sort still work but i have no blown fuses that I've seen and I'm now at a loss. Usually I don't feel this dumb but it's one thing after another here. Anyone have any ideas? I did some searches but probably didn't word them right.

Welcome to SteelSoldiers.

Make sure you visit the Cucv Wiki - Steel Soldiers::Military Vehicles Supersite (CUCV Wiki) that is at the top of the page on the CUCV Forum.

All of the CUCV Technical Manuals are listed and many other helpful bits of information.

Make sure you download the repair manuals. You can get then for free. A couple of our members have posted them on their websites.

Also the wiring diagrams are in the appendix of the -20 and -34 manuals.
JATONKAM35s HOME ON THE WEB

Also checkout the http://www.steelsoldiers.com/cucv/20600-faq-thread-cucvs.html stickey. It is where we try to post helpful tips and tricks.

Almost every question you will have has been asked and answered many times. The advanced search will become your best friend. Please don't hesitate to ask something that you can't find.

Read the TM 9-2320-289-10 Operators Manual to find out how a stock system should work. It is simular to the Operators Manual for Civilian vehicles. It tells you where all the lighs, switches, etc are located and what they do.

Three of the most important tools you can buy are:

Voltmeter and know how to use it - ~$10 and up
12v Battery Charger - ~$50 for a decent one
Battery Load Tester - ~$30 for an okay one at Harbor Freight


There are some fusible links that will blow to protect circuits. They in the engine compartment.

Have you ever removed and cleaned ALL the fuses in the Fuse box? What about cleaning the fuse box itself?

I've added you to the Oklahoma Convoy members list. I send out notifcations of local events thru out the year.

 

[SGT Estum]

If my memory serves me correctly, the GEN2 bulb and GEN1 bulb are different. I think GEN1 is a 168 and GEN2 is a 194. Even if you put the wrong bulbs in, I don't think it would cause you this problem.

I would pull the alternator and have it tested at your auto parts store to rule that in/out.

Next pull the two wire connector and check for voltage -- one wire should have front battery voltage with the key off and the other wire should have front battery voltage with the key on. If this is not the case, then your alternator is definitely not getting excited.

 

[Andrewr205]

I am having a similar issue. No gen 1 light after having my batteries die. I tried charging them and it was no hope so I had to replace them. Now I’m only getting the gen 2 light to come on. But both batteries are charging and the truck is operating perfect. I am getting 13.8V on the front battery and 14.8V on the rear at idle. Could my front battery still be charging even with the light not working? I tried swapping the gen 2 bulb into the gen 1 socket and that still didn’t fix it. My heater fuse is good and I can’t find a burnt fusible link.

 

[Keith_J]

13.x volts at the battery with engine running means either a weak alternator, discharged battery or bad connection.

With key switch on, engine not running, you need battery voltage at both regulator connections on the side of the 27SI alternator. These circuits are the dash lamp (excite wire) and voltage sense (connects to battery + through a fusible link).

13.x volts at the front battery positive terminal can be caused by a prior owner trying to make the alternator a single wire type. Measure voltage output at the main output of the alternator. If the alternator terminal is 14.4+, you have voltage drop over the #6 wire to the battery.