Alternator Light comes on when accelerating

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radiantgal@gmail.com - 31 Mar 2006 19:09 GMT

Hi,

I have a 1998 S70.

I was in the mountains last week where the temp was freezing or below.

Since I have come home the alternator light comes on when accelerating
from a stop and then and goes off after about 5 seconds when I step on
the gas.

My mechanic said battery and the alternator tested ok. He works mostly
on BMW's
these days, however started his business working on Volvo's.

Should I be concerned?

Any suggestions?

Thanks,
Radiant Gal in California

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zencraps@comcast.net - 31 Mar 2006 20:55 GMT

The most logical thing would be to look for a loose or glazed drive
belt.

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Peter K L Milnes - 01 Apr 2006 01:25 GMT

The onlky thing I can think of is that the alternator drive belt must be
slightly under-tensioned. That is looser than it should be!

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).

> Hi,
>
[quoted text clipped - 16 lines]
> Thanks,
> Radiant Gal in California

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Michael Pardee - 01 Apr 2006 02:55 GMT

> The onlky thing I can think of is that the alternator drive belt must be
> slightly under-tensioned. That is looser than it should be!
[quoted text clipped - 3 lines]
> 700/900/90 Register Keeper,
> Volvo Owners Club (UK).

BTW - a good "shadetree" test for a slipping belt is to try to turn the
alternator by pushing on a cooling vane (right behind the pulley) with a
thumb. If the alternator moves (and the belt does not) the belt is either
too loose or worn out.

Mike

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Michael Pardee - 01 Apr 2006 02:57 GMT

> Hi,
>
[quoted text clipped - 16 lines]
> Thanks,
> Radiant Gal in California

Besides the belt concern, it's possible the engine ground is bad and the
engine is getting a stray ground until you make it work and torque to one
side. The ground is a braided strap under the car in the older models but I
don't know what it is in the S70.

Mike

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User - 01 Apr 2006 08:58 GMT

> Hi,
>
[quoted text clipped - 16 lines]
> Thanks,
> Radiant Gal in California

I'd guess that the d+/61 wire on the alternator is chafing/chafed
somwhere and that when the motor rotates under starting load it shorts
to ground and causes the light to come on.

Bob

Signature

The goal when driving is to miss the maximum number of objects.

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Mat-nospam@earthlink.net> - 01 Apr 2006 20:08 GMT

>> Hi,
>>
[quoted text clipped - 22 lines]
>
>Bob

Although Bob is probably correct --- in a Porsche I own the flicker
and intermittent light on acceleration was finally diagnosed as being
a screwed up 'diode block' (or the solid state equivalent) --- the
alternator was occasionally dribbling out some AC current.

It might be something to check on after you're sure that the chafed
wire isn't the culprit, ( --- AC can fry the engine mgmt system).

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