v8_ranch

I have been on Rennlist for several years, but in the 911 group until now... recently picked up my first Shark...

So, I inherited what is shown in this video when I got this 1984 from the previous owner a few months ago. From what I am told, it is a GM alternator and it looks like he got it mounted well as far as brackets and alignment. No squeak or noises from belt when it runs. But wiring has a flaw as it is not sending anything to the battery while car runs (11.85vdc at the battery). Does anyone see anything in this video that looks amiss about the current wiring? (video was too large to upload, so here is YouTube link)

The Forgotten On

Does it illuminate the low voltage light on the gauges at all when it is running?

If not then the alternator exciter circuit isn't working and the alternator wont excite and do anything.

Could be a burnt out bulb in the cluster, or bad wiring.

v8_ranch

Don't believe I saw the light illuminated, but I know the VM reads nothing on the dash.

Landseer

I've installed 3 of the gm alternators on different 84 cars.

Cant see from your video. But generally there is a plug in pigtail. Only L terminal is used. That connects to the small harness wire, black?or purple? That is exciter an runs up to 14 pin connector, then on to ce panel, then to voltmeter. We can trace that if needed. Only other connector is hot lead in harness connects to + terminal on back of alternator. I've had to switch out my harness lug with a more suitable size.

I think I used 105 amp alternator for 88 or 89 camaro.

Even if exciter doesnt work due to corrosion in 14 pin, Revving motor to 2500 or so should self excite the alternator. Might need to swap alternator, should work, proven substitute.

v8_ranch

Hey Landseer, thanks for that info... and dang, almost local, haha... Wish I was up in your area. The PO installed the CS-130D GM alternator and looks like he did a good job as far as mechanical alignment, etc. After reaching around later today I finally discovered no pigtail installed. So I ordered the one from Painless based on another recommendation... I got the Painless 30705 2 wire pigtail. They were recommending (as well as another 928 owner) to use the two wire, with the 85 ohm resistor inserted in the line attached to L pin, and then tie that, the wire from the I pin, both to the 12v keyed supply... Is there a reason not to do it that way?

My pigtail will be here Monday - hoping it not being connected properly by PO didn't damage the new alternator...

vanster

Invest in a Greg Brown alternator. You won't regret it.

WestInc

I've also mounted a delco/Gm 130 alternator on my 1983 928s, works perfect. I have checked the temperature on it on idle, car standing still and it is not overheating in 21c ambient temperature. Chargemeter also works as it should. It is fully charging on idle regardless of me having fan on full, highbeam on, stereo etc. Very easy conversion with the brackets. Did my own "pigtail" cable (L-pin, no resistor) with waterproof connectors. Also mounted some dust/gravelcovers as the backshroud doesn't fit the new alternator...

v8_ranch

WestInc,

Interesting, so, how long have you had the GM alternator in service with the single 12v wire and no resistor?

WestInc

Some small drives round the village, many testruns in the garage. Every measurement concerning voltage/amps checks out. I basically followed the instructions from this post:
taking the CS130 alternator plunge - Rennlist - Porsche Discussion Forums

WestInc

Very basic explenation how and why it works.
Alternator Trouble shooting (hubbardhobbies.com)

Petza914

Does your car by chance have led bulbs in the gauge pod (nice, bright lights)? I believe the exciter circuit includes the incandescent charge warning lamp and if it doesn't see resistance from that bulb won't excite, but someone will correct me if I'm wrong.

WestInc

If you ask me, no led's in my pod. But IF you have led-bulbs you're quite right. It is described at the end of the page in this link...;
http://www.hubbardhobbies.com/novapi...oubleshoot.htm