Electrical Alternator Help

mgbruno · 07-05-2006, 06:55 AM

Hi All,
I posted another thread "Help from the Experts" concerning my alternator woes. I have some figured out but it was recommended to me to post another more specific thread. Here is my status:
I just installed a newly rebuilt Paris Rhone Alternator. After many attempts, I finally figured out what I was doing wrong. You know, the little key in the shaft - the one that turns the alternator? Well, my old one had the key in it. My new one did not. I of course did not notice this until I had spent countless hours trying to figure out why the new alternator wasn't generating any electricity! Duh! Of course it couldn't - the fan couldn't turn the alternator without the key

Anyway, now, the alternator is generating about 13.6V at idle and 14.8V at 200RPM. The battery light is also off when the car is running. But strangely enough, as soon as I connect the battery - even with no key in the ignition, that darn battery light comes on!!! What on earth is happening? Anyone here have any ideas. If none, I plan to take everything apart yet again. Then with no alternator connected, I'll connect the battery and check the light. Then I'll hook up the alternator but not continue the install. Check light again. And so on... Any ideas would be great.

Thanks,
Mike

rick-l · 07-05-2006, 07:00 AM

Old Thread

cmonref · 07-05-2006, 04:18 PM

With everything connected, ignition OFF, and alternator light ON, you have a shorted positive diode. Pull the oil press/temp guage and remove the alternator light. With ignition OFF and +12v on the BLUE wire, that shows the shorted positive diode.

Pull the alternator, leave it hooked up. Ignition OFF and +12v on the terminal with the BLUE wire (D+ terminal), again shows the shorted positive diode. D+ should not have voltage on it with the ignition off.

At least this description above is what I had a month ago. Warranty exchange fixed it.

mgbruno · 07-06-2006, 03:33 AM

Brian,
Thanks so much. At least this explains it - I think. You know, I did check the voltage going through the D+ (Blue) wire. With it unconnected to the alternator, there's only about a volt going through it. With it unconnected, there's 12V going through the Blue wire. I just had a thought though using your advice. The blue wire had a small rip in the casing, so I cut it and spliced on a piece of slightly heavier guage wire. Before I had spliced on this wire, there was only .46V going through the Blue, when connected to the alternator. After I spliced, there was a little over 1V going through there. Maybe the heavier guage wire is allowing too much voltage through and therefore these symptoms. Boy, am I sounding like i know what I'm doing or what!!! I bought the alternator off a guy here on Pelican. It was a rebuilt one and looked brand spanking new. If it is a shorted Positive Diode, and if its expensive, maybe I can get the seller to pay. Hopefully not necessary though. Rather not go through that. Regardless, I will have to pull the thing....again. Anyway, I'll keep you guys posted. thanks so much for the help.

Mike

Par911 · 07-06-2006, 05:13 AM

free bump for Mike.....good luck with the alternator troubles.

rick-l · 07-14-2006, 07:56 AM

did your cab ever get a new alternator?

mgbruno · 07-17-2006, 03:41 AM

Nope Rick,
I had someone look at it over the weekend. Supposedly an expert. Told me nothing I didn't know already. This time its still out of the car but in the housing. Am going to take it to Autozone now to at least see if they can check it. At least I'll know if its the car or the alternator. Just been too busy.