Gen 1 light on but appears to still be charging.

[Barn Owl]

Hello to all here, I have finally been stumped to the point that I have been forced out of lurking and am in need of assistance. I have searched and read many threads and I haven't found much on Gen 1 circuit problems. I own a 86' 1028 with low miles, but it's starting to act like it has a several hundred thousand. Not knowing what information I need to post please forgive me for throwing it all out there. Possibly unrelated, but the back story is that several weeks ago the less than a year old #1 battery (closest to the front) went to zero volts over a few days. I thought it was a bad battery and replaced it with another new one. I immediately noticed that the Gen 2 light was on with the key in the off position. It seems that judging from the sound, a relay was sticking under the dash, and after "exercising" it for several cycles it seems to be working fine and the light now works as it should. Several days later I took the truck out and noticed that the Gen 1 light was dimly on and that it's brightness was directly related to the engine RPM's. I have the TM manual and following the procedure listed I disconnected the pug and Gen light remained off with the key in the run position/engine off. I am not sure exactly how to trace the wiring at this point and the manual says if that is OK then replace the alternator. My dash voltage meter is showing the needle on the white bump in the green, and both batteries are staying fully charged. What could cause this condition? Is it in the wiring or a failed component in the alternator? I don't know what is "normal" so here are some other observations. I have noticed several years ago that the dash volt meter does not go to full green until the engine is revved up a bit, but once there it stays. Possibly also unrelated, starting about eight months ago, the wait light comes back on for one more cycle after the engine starts. The glow plug relay on the firewall was replaced last year. Thank you all in advance for any help. If it where not for forms like this it would be extremely difficult to own and maintain one of these pieces of history.

 

[stationjj]

If you haven't already read the Barrman post listed above in the sticky's. Lot's of good information You may or may not find the answer to your problem directly. You will learn about the crazy CUCV electrical system. It may lead you to your problem indirectly?

Good Luck.

stationjj

 

[dependable]

I would second you reading all the 'stickys' at top of CUCV forum, a few of them relate to your problems. There have been so many threads about these topics that it becomes tiresome (no fault of yours, but it is best to read up). An actual understanding of system will serve you well. Probably will need rebuilt alternators or at least new alternator diodes, but without understanding system, you will just be parts swapping. Also, be careful of mis matched batteries. If they are of different values, both will fail prematurely.