Alternator idiot light help needed .

[ppetion]

Wiring my alternator on my 3.2 conversion. I know that the 3.3 has a built in VR on the alternator. Here is how it is wired ( see pic)
For some reason the idiot light will not come on.
What am I doing wrong here .

[clarkd]

Race car dash Alternator Light

Look at the picture in post #6 of this thread.

[ppetion]

Thanks ,

I think I see where I messed up . The other side of the idiot light goes to positive not ground . I'll correct and report back .

Just to clarify , on the 930's, if the system is functioning properly , when the key is in the "on " position , the idiot light should lit and goes off when the engine starts . Am o correct ?

[Joe Bob]

Yes, the operable light is part of the charging circuit. Once hooked up and lit, start the engine and test with a meter at the battery terminals. Should see 13.8v plus. Over 14.5v and there may be an overcharging issue.

[ppetion]

Still no go . is there a ground wire coming from the VR to the relay box area ?

[timmy2]

Is this going in your '70?
Are you trying to use the remote VR?
Your drawing by doesn't make sense for using an internal VR.
If for the '70, you need to remove the old VR wiring from the VR on the panel and make sure the blue wire is isolated and goes from the back of the gauge to the 14 pin connector.

[ppetion]

Yes Tim , it is for my 70 and I am not using the remote vr. The remote VR has been removed
I was wiring it according to this diagram.



If I understand you correctly , pin 14 of the 3.2 engine harness (red power always on) goes to the light on the gauge ?

Is the other side of the light gauge grounded or another positive ?
Thanks for your help .

[Joe Bob]

Stupid question, I assume you have tested the bulb on an independent 12v power source to see if it works?

[ppetion]

There are no stupid questions especially when dealing with these old wirings , one can get confused and miss the smallest thing . But yes I have .

[Joe Bob]

Good....sometimes while searching in the forest you miss the mushrooms.

[timmy2]

The power to the gauge idiot lamp normally comes from the multi gauge power harness in the dash wiring. (Blue/yellow and blue wire in the photo from SL35 1970 wiring diagram)
The constant power on pin 14 runs to the rear fuse panel.
Send me an email or PM with your phone number, happy to walk you through it.

[timmy2]

Hmm, photo isn't uploading, no check mark ✅ when it says it is done.
Trying again...

[ppetion]

Sending pm

[ppetion]

Thanks all who helped . The blue wire on the short relay board harness was crossed from pin 11 to 9.

Problem solved !

[Bob Kontak]

Originally Posted by ppetion

Thanks all who helped . The blue wire on the short relay board harness was crossed from pin 11 to 9.

Problem solved !

Nice work!

[timmy2]

Good talking to you and texting back and forth on the phone.
Always a barrel of monkeys when someone has been there changing things before you touch it.

[Dmitry at Pelican Parts]

If anyone needs some more information on replacing the alternator or a visual guide to troubleshoot, please take a look at the link below. Please note that we also have other articles on the Alternator as well.

Porsche 911 Alternator Troubleshooting and Replacement | 911 (1965-89) - 930 Turbo (1975-89) | Pelican Parts DIY Maintenance Article


-Dmitry