gen 2 light staying on

[bodiman]

I've been noticing that the gen 2 light is staying on after the vehicle has been running for a minute or two. not being totally knowledgable on 24 volts systems, I wondering if this is normal. when is does go to charge the volt meter goes to green and i can hear a solenoid chunk. I wondering if this is normal or I have to find the problem. i check for voltage at both alts with the key off only alt 1 has 12 volts at the big wire, single post. Can anyone give me some ideas of what to check or look for?

 

[Warthog]

The light comes on to show you there is a problem. It could be that your alternator needs to be rebuilt or it could be as simple as a dirty connection.

Read the stickies in the CUCV forum to help you understand the system.

Barrman has a great stickie the explains the charging system.

 

[renovate7]

I just had the same problem on a 1008 that has been sitting a long while. Light was on and Gen 2 showed battery voltage, not 14v+. After a few starts it started working. I believe there is a relay in the system that must have been sticking. I haven't taken the time to find it as Gen 2 is working...I am now getting ready to replace the glow plug relay. It was sticking and making the wait light stay on for more than 20 seconds. I tapped it with a hammer, as we used to do with Ford solenoids way back when, and it started working but is going to get replaced anyway. Even working I'm only getting 10 volts or so out of it, may be burned contacts inside. When I got this the resistors had already been bypassed by the Military.

 

[bodiman]

up date! had alt check out, all good! cleaned all terminals reinstalled now alt 2 does not turn the light out at all! voltages coming into alt is 13.8 nothing coming out. exciter wire is 12 volts, at unplugged and key on! i guess i need wiring diagram! where can i find that?

 

[Warthog]

The Tech manuals have the wiring diagrams.

TM 9-2320-289-20 and TM 9-2320-289-34. The diagrams are in the appendix. Click on the link at the top of the page for the manuals.

Is you truck wiring stock or has it been modified? On the GEN2 alternator the excitor plug should have 24v ate the red wire at all times and 24v at the brown wire only when the key is on.

Can you post some pictures of you alternators and wiring?

 

[bodiman]

thanks the exciter plug has only 12 volts, actually 11.6 volts when I turn on key the brown wire has only 2 or 3 volts. maybe this is my problem?

 

[bodiman]

thanks the exciter plug has only 12 volts, actually 11.6 volts at the red wire. when I turn on key the brown wire has only 2 or 3 volts. maybe this is my problem? the truck is stock

 

[bodiman]

no I checked it wrong the exciter plug red wire is 24 volts all the time but the brown wire with the key on is only 12 volts

 

[Warthog]

Is this a new problem or has it always done it?