Alternator light

[Dieselumbrado]

When I turn the ignition on, the alternator light on my diesel 82 Rabbit goes out right way, it just stay on for a second, the oil light remains on until I start the car.
Have anyone experienced this problem?

[Rabbit TD]

I don't know if you are typing what you are thinking but naturaly the oil light will stay on until you start the car as the engine doesn't have any pressure in it before that to turn it off.  As for your alternator light going out right way after you start it you must have a pretty good one because it is very common for these Rabbits for the light to stay on till you blip the throttle just a little, seems like they all do it.

[Vincent Waldon]

I think the OP is saying the BAT light goes out by itself with the key in "ON", engine NOT started, where as the OIL light stays on until the engine IS started. as per normal.

[Rabbit TD]

I think the OP is saying the BAT light goes out by itself with the key in "ON", engine NOT started, where as the OIL light stays on until the engine IS started. as per normal.

Somehow I missread that and I looked at a few times before I answered.  I would at least check the battery voltage with a voltmeter with the engine off and running to make sure the alternator is charging though.  Could something in the internal regulator cause that?

[Dieselumbrado]

The battery is okay, I changed the alternator, and it's light stays on for a moment, and then goes off before I start the engine.
When I start the engine, the alternator light's still off, even though the alternator is not charging (I checked that with a voltmeter).
I have to rev the engine higher than usual for the alternator to charge.
What could be the reason that the battery light doesn't stay on like before?

[Vincent Waldon]

The alternator light should *not* go out by itself until you start the car... so unfortunately you've still got a problem someplace.  

If you're convinced you've got a good alternator then you'll have to work backwards... wiring to the cluster or the cluster itself.  The alternator light is how the alternator gets enough voltage to start generation... with this not working you'll need to rev the alternator a lot to get it to start charging.

[burn_your_money]

Try running a small ground wire from one of the alt casing bolts. I think there are 4 of them around the perimeter of the housing held on with 8mm nuts.

Either ground it directly to the block (I went to the vacumm pump) or to the battery. This solved my need to blip the throttle. Once it starts it takes about 1/2 a second and my tach is up and the battery is charging. I doubt it will cure your battery light problem though.

[Dieselumbrado]

The alternator now is charging and it's light stays on until the engine start.
I was checking the wire harness that goes to the alternator and noticed a lose wire that was wrapped around it, and the only place that I thought it would go was the W terminal in the new (rebuild) alternator, but the old one didn't have this terminal, maybe the previous owner changed.
I started the car and now I don't even need tho tap the accelerator pedal to wake the alternator, and is charging around 13.75 v as soon the engine's running.
But now, the oil light stays flickering, but dimmed...
Is any relation between the alternator and the oil light?
I'm going to use the car tomorrow and see what happens.
BTW, I bought the alternator at Advance AutoParts, and while I was there I got 5 qt of Mobil 1 TD 5w40 oil and a Mobil 1 oil filter for $29.99 (+ tax) that was on sale, I thought is a good deal, that's why I'm telling you, if somebody is interested.

Thanks for your help and attention!