The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Generator light is on.

Okay, I haven't been on here for a while, things have been smooth. That changed on Friday. Driving my 66, the battery gauge suddenly jumped really high, then dropped really low - never came back up. Took things apart today to find that the hot lead on the alternator is melted out - I mean gone. Took the alternator apart to find that a wire on the inside had actually grounded to the casing, which likely has been a problem for a while.

So, I got a new (rebuilt) alternator in it. Everything hooked up okay. Started the truck, and the generator light is on. First time I have ever seen this light. Battery gauge is showing around 7, which I knew would be low as I only had it on the charger for about 30 minutes. All electrical items work. Ammeter is barely above 0, but does go up when I give it gas. Just want to know, is the generator light on because the battery is low? Or is there another problem?

I forgot to mention that it has an external voltage regulator.

I disconnected the positive battery cable while running, and it shut off. So, I got a bad alternator? Would a voltage regulator do that?

The regulator controls what the alternator does. Last one I got was solid-state...no moving parts, light weight, and cheap. FLAPS or local generator shop might be able to test both components. Hopefully, you don't have harness issues.

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Had the new alternator and battery tested yesterday. Both tested good, but no voltage was going to the battery. I am thinking regulator. There are no obvious signs of wiring problems to the regulator,

read this entire thread here :

1965 C10 - alternator or battery...

Pay close attention to the troubleshooting posts by wrenchbender ret.

The external voltage regulator can go out and the wiring may be fine.

Let us know what you find out.

-W

Okay, so I put a new Borg Warner Voltage Regulator on last night. Started her up, and the generator light went off. Battery charge gauge was showing 13 volts - looks like problem solved.

This morning, I decided to drive her to work. Same thing - no generator light, battery gauge reading steady at around 13 volts. However, as I slow down, and the rpms drop below 2000, the battery gauge is jumping to 15 or 16. As I accelerate, the needle creeps back down to around 13.

There is also a humming sound coming from the engine bay that I had not heard before? Do I have the alternator belt too tight?

Update: When I got the truck home, the hum or whine started again as I put it in the garage. I noticed that while it was whining, the generator light would flicker on. I am at a loss here.

Okay, so doing the alternator/regulator field test, I found that there is a magnetic pull at the alternator with the ignition off. The material that I am reading says that this is not supposed to be, but does not say what may be the cause. Any ideas?

So you mean that their is a drain through the ac gen?

There never should be a drain through a ac gen with the ignition off. You have a bad ac generator.

Hi, Frank, First to the voltage spikes, check ALL connections both positive and negative from battery to frame to engine for tightness and being clean. Next, if the generator light bulb socket in the dash has a outer rubber cover, check that it is not touching ground, also the wire to the outer part of the socket is also not touching ground. If it does it will turn off the rectifier and stop the charging and turn the light on.

Here is the update.

The whining noise is coming from the voltage regulator. When this noise happens, the battery meter is jumping up and down.

I tested all connections and grounds. All checked out. I even added a ground from the negative battery terminal to the body of the voltage regulator. Still no change. I bypassed the voltage regulator and confirmed that the alternator is pushing 14 volts, and the battery reads 14 volts.

I replaced the voltage regulator again. The one that I took off had signs of heat on the back side. Put the new one on. Start up the truck and the volt meter shows 14 volts at the battery. No generator light; no noise. Turn it off, and then back on. Generator light comes on for a few seconds. At the same time, the regulator whines, and the volt meter drops to 12.5. Then, on its own, the generator light goes off, whining stops, and volt meter goes back up to 14.

I continue to be at a loss, and do not know if I should be concerned, or just leave it alone as the battery is charging.