1993 850 GLT Alternator?

This car has always had a pulsing effect noticeable at night when the
lights are on, and there's an intermittent whining noise from the
engine compartment - the alternator I suppose.

I also get a battery light fault indicator on the dash when I stop at
a stop sign or red light that goes out immediately upon acceleration.

It's been like this for months.

The battery is always fully charged and never fails to start the car,
and nothing else ever goes wrong, but it's a bit puzzling.

If it were an older car, I'd change the voltage regulator. Is there
such a part on this car or is this yet another onboard computer, or
sticky relay, doing it's weird thing?

 

It very much sound like the voltage regulator. Wake Up! This is an
older car. Shops normally test the voltage regulator, alternator, and
battery at the same time. Most shops can do this. Places like Sears
will do it for free. If you don't trust Sears, you can go someplace
else for a second opinion.

 

Yes, he should have it tested, but I am not cetain that a place such
as Sears or a local car parts store will be able to tell him whether
the voltage regulator is the problem.

I say this because in my experience, when having Schucks (car parts
store, member of CSK family) test alternators, the result is only
PASS / FAIL.

The OP's issue seems a bit too suble to be detected by less than an
auto electric shop, or a least someone with a good knowledge of auto
electric: which chain store clerks do not have.

Amazing how many people cannot fathom a VOM.

 

_____
You don't tell us how many km or miles the car has on the odometer.
Your car may have 230,000 to 300,000 km on the clock. In my experience
a Volvo brand (Bosch) alternator will need a new set of brushes in the
voltage regulator module at about this kilometrage. The module is
usually simple to pull and check. If you are handy with a soldering
iron, you can install new brushes for about $10. Go to you local auto
electric specialist, and ask the alternator technician for a new brush
set. Bring the old ones with you as a sample. The voltage regulator
modules do fail, but not very often. A new module costs about $25, but
that is overkill. Finally, check the condition of the slip rings in the
alternator. If they are not scored more than, say, 0.5 mm, then all is
well. A bit more scoring can be corrected by machining the armature
during a rebuild. The cost for a rebuild is usually $100 (new bearings,
machined armature, bead blasting, full load testing on bench).

/ J

 

I have had experience at Sears. Since they mostly sell batteries and
tires, they are anxious to find out if the reason a battery fails is
because the cars alternator or regulator is bad. For that reason, they
have great diagnostic equipment that their "mechanics" can use. They
also use this before installing a battery to make sure the car doesn't
ruin the battery. They usually recommend taking a car with a defective
voltage regulator to the dealer for service. They mostly want to sell
batteries and tires.

 

What I meant was if this was a car from back in the 60's or 70's, when
most of my automobile repair knowledge was learned, hahaha.

 

Thanks for this and thanks to all who responded.