Gen 2 lamp questions

[twomorestrokes]

Not sure if I have a charging issue or not. The Gen 2 lamp has NEVER illuminated on my truck, even during the initial key on/ engine off test sequence. Truck always starts and runs fine, but lately the volt gauge doesn't quite make it into the green zone. Worked this way even after rebuilding my instrument cluster and replacing all bulbs.

This morning I got in the truck to move it and both Gen 1 and Gen 2 lamps lit up when I turned the key on. Truck started fine but Gen 2 lamp stayed on after it was running. Within the first minute of running, the light went out and the gauge went fully into the green zone. I checked again later and the same thing happens. Truck seems to be charging better than ever after the glow plugs stop cycling. Is this normal operation for the Gen 2 lamp?

Yes, I tried a search. Thanks.

 

[Warthog]

Sounds like you have/had an issue with GEN2. More thank likely the 2pin connector on the alternator.

The bulbs MUST work on both GENs for them to work. No light no worky.

The lamps should go out imediately after starting. Sometimes you have to increase engine speed to get the alternators working and for the lamps to go out.

Have you ever rebuilt the alternators? Tested the GEN2 circuit to see why the lamp wasn't working?

 

[Keith_J]

I'm seeing this problem too. Lamp checks out, no voltage to brown wire on the 2-pin. But both alternators are functioning fine. Yes, it requires a blip on the throttle to bootstrap the alternator. I'm beginning to think it is the alternator relay not making proper contact.

 

[twomorestrokes]

I just tried it again. The Gen 2 lamp is turning off faster after start up every time I check. The volt gauge is over half way into the green. I am beginning to think that the system just started working correctly this morning. Would the truck be drivable with only Gen 1 charging? I've put a couple thousand miles on this truck with no issues other than the volt gauge staying near the top of the yellow just under the green.

 

[Warthog]

You don't have to have either alternator working to drive the truck.

Only time the rear battery is used is during starting and GP operation. A fully charged rear battery can last a long time.

The front battery is used all the time. If it runs down the truck will stop running as the injector pump fuel shutoff needs 12v

 

[twomorestrokes]

You don't have to have either alternator working to drive the truck.

Only time the rear battery is used is during starting and GP operation. A fully charged rear battery can last a long time.

The front battery is used all the time. If it runs down the truck will stop running as the injector pump fuel shutoff needs 12v

I realize the truck will run a while with no alternator output, but I drive this truck up north on weekends at night. 2000 miles of 200 mile round trips so it must have been charging.

Thanks for the info on what the two different batteries are used for and when.

 

[MakersTeleMark]

I like to swap them every 6 months or so, or by mileage, whatever occurs less. Keeps them even.

 

[twomorestrokes]

I like to swap them every 6 months or so, or by mileage, whatever occurs less. Keeps them even.

I've read that it is a good idea. My batteries were brand new military units when I bought the truck.

I drove the truck for awhile last night. Definitely working better than ever! Thanks for the info.