Way back in the past I have run into this and in my reading there was
something about brushes "floating" when they are almost gone. Can't
remember the details, but probably related to how much tension is in the
springs holding the brushes in place when they are well worn. It may
very well be time to change the brushes. If your alternator is original,
given the age of our vehicles it's probably time to change them, if for
no other reason than to ensure you don't breakdown at some inconvenient
place.

Regards,

John Rodgers
88 GL Driver

DaBomb wrote:

>OK, I looked through the archives for the past three years about my current
>issue, and though many postings were helpful, none illustrated *exactly* the
>problem I'm having.  Here goes:
>
>At higher rpms, say 3,800 to 4,000, my alternator light comes on.  I usually
>drive around 3,500 so the light will come off after I've completed shifting.
>If I drive any faster than 70 mph, the light is sure to come on.
>
>I recently replaced the batter as of last week.  My mechanic -- a VW
>air-cooled specialist, not water-cooled -- tested the alternator while we
>had the car running with the lights on and air conditioner as well and he
>said the alternator checked out fine.  As did the regulator.
>
>>From what I can tell from the archives, it could be brushes or an
>alternator, despite the readings my mechanic is getting.
>
>Has anybody had this problem?  Please advise.
>
>
>
>
>Love and Rockets,
>DaBomb
>'89 Vanagon GL
>
>
>