Abdiel Gonzalez

Hi Again

This is my second attempt to get help on this.

I've read, I swear a lot, and perhaps I think I understand how the charging system works now, I just want to confirm my theory is right.

IN the attached picture there are 3 points

Black is Negative
Red is B+
Yellow is the cluster bulb

Is it right the cluster bulb is a negative lead to the alternator, and a positive lead in the other end, that turns into a positive when the car starts and the light goes off?

My car is not charging at all, and the light of course is not turning on. If I use the tester and check continuity with the car off, between the black lead (ground) and the yellow lead (bulb) it is correct that we should have continuity with the car off?

I am at the point of buy a new alternator, but I need to make sure thats the problem first.

ONe more time, thanks again

rusnak

What year is your 911? Have it tested for free at your local auto parts store.

Abdiel Gonzalez

1982, 911 SC Targa

ron mcatee

Test it free at Autozone.

TerryShugart

The auto zone suggestion is a good one. But to answer you question, you should have 3 leads on your alternator. D+ (blue) goes to the dash light and the regulator. D-(brown) and B+ to the battery. When you turn on the ignition you should have the light come on as you don't have voltage on D+. When the engine starts and the alternator turns it will put voltage on D+ and and the light goes out.

Abdiel Gonzalez

Thanks

Maybe you haven't seen but I am not US based. We have had the alternator checked, but the D+ lead should be ground when car is off, right? and Positive when Alternator is spinning. I purchased a new alternator already, so expecting to come on the mail soon.

Thanks in advance.

TerryShugart

Yes. ground potential when the engine is stopped and positive when the alternator is spinning.
While you're at it I suggest you check and confirm a good ground from the engine case to the alternator housing. This is a problem I just fixed on mine after years of poor charging.
Good luck

76FJ55

Did you ever run the tests I mentioned in your previous thread to determine that the charge indicator light was working correctly and providing the necessary 12V to the alternator via the blue wire?

You need to ensure that the charge light is working correctly, or it is unlikely that the system will charge even with a new alternator.

If you need any more details than what i put in your other thread, just let me know.