It only glows when the revs are above 2800rpm, and then turns off when the rev counter is below 2800 rpm. So I guess it is a loose alternator belt, but I guessed wrong. I did tighten the belt becasue it felt a little loose, but the problem persists.

So I replaced the voltage regulator with a brand new one. Same conditions, dash light glows above 2800 rpm.

I think the only thing left to do is replace the alternator….ugh….am I right?

Is intermittency a known failure mode of alternators? I always thought they worked or didn’t…not something in between.

Illuminate me pleez…

Oh man, I am having alternator problems as well. I have replaced the VR, relay board, re-tightened all of my grounds, cleaned and checked all the fuses and contacts and still get nothing at the battery. This is a brand new alternator even. I'm going to swap it out Thursday or Friday..........

And I have been told both. A guy here in town who rebuilds them said that it should just fail but they have been know to act erratic.

I had problems like that with my 911. Turns out mine was overcharging 16-17 volts. What does your voltmeter say when the light is on?
cheers, Elliot

Marginal brushes in the alternator sometimes cause an intermittent light (and intermittent charging). As the brushes continue to wear, you'll eventually get no charging. You should be able to get the alternator rebuilt. This place: AutoLectrics, Campbell, CA, (408) 559-3540 comes well recommended by the 912 crowd for doing this kind of thing.

My last alternator replacement (twice!) was really 3 (count 'em- three) bad new bosch voltage regulators.
Its worth it to try another....

With so many bad Bosch VRs, I'd start considering using something else. Other companies besides Bosch seem to be capable of making reliable VRs that aren't bad in the box, and just about any VR should work.

QUOTE (lapuwali @ Jun 7 2005, 04:01 PM)

With so many bad Bosch VRs, I'd start considering using something else. Other companies besides Bosch seem to be capable of making reliable VRs that aren't bad in the box, and just about any VR should work.

example?

Example? GM, Ford, Ferrari, Dodge..




M

Get a Borg-Warner (Part # R588) electronic voltage regulator and be done with those huge electro-mechanical fossils.

Works fine, lasts long time.

I think it's a problem with your wiring harness - some guy on this board makes replacements...

bout to say somethin' sim'lar!


M

QUOTE (Rouser @ Jun 7 2005, 02:50 PM)

Get a Borg-Warner (Part # R588) electronic voltage regulator and be done with those huge electro-mechanical fossils. Works fine, lasts long time.

There you go. Figured you'd pipe up, Rouser. I remembered you posted this before, but couldn't remember the part number.

If you need to replace the alt you may want to consider getting a high output one from davep. His quality is very good. I am sure there is very little chance of an early failure with his since he does the work himself.

I have not had to utilize the HO but I expect it to be valuable when I get around to upgrading my headlights.

-Jeff

You could kill two birds with one stone. GM 1 wire alternator with lots of flavors of output, like 90 to 140? Brad had wrote up the modifications some time ago to get it in place, and if I remember right there wasn't too much to modify.

QUOTE (redshift @ Jun 7 2005, 06:23 PM)

bout to say somethin' sim'lar! M

One time, I was about to develop this theory, but this Einstein guy said it first...