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paulhide · Posted: Wed Jun 30, 2010 6:05 am Post subject: Alternator question. Anyone?

Last night I noticed my alternator charge warning light actually pulsing about once a second. (Just lights on - no fan or windscreen wipers) Does this mean that there's a problem with the alternator/regulator?
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Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

While idling?

Did you check the voltage of the battery while idling and while you increase the revs to see the voltage increase?

Mine is about 12.3 - 12.4 while idling and increases to about 13.8 when the alternator kicks in.

I see this pulsating light sometimes, but when I check the voltages all seems ok. Maybe just a very sensitive sensor/regulator.

Question for you Paul: How do I disable the automatic lights on function? I really don't want my headlights on all the time (drains the battery and wears out the bulbs).

paulhide · Posted: Wed Jun 30, 2010 1:37 pm Post subject:

Didn't know that the cars ever came with an automatic lights-on function. You sure it should have?

Just been told that the pulsing may be down to a faulty diode in the regulator on the back of the alternator. Can anyone confirm this?
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Brit01 · Gold Cloverleaf Joined: 24 May 2010 Posts: 665

Oggie · Posted: Wed Jun 30, 2010 6:07 pm Post subject:

Not in the UK they don't, my lights have to be turned on....................with a switch of course lol
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ZeNiTh-PbArM · Posted: Wed Jun 30, 2010 6:34 pm Post subject:

hi, one pulse per second is waaaay to slow to look like a burnt diode. It looks like the typical response time of the regulation circuit in the regulator. I would look for a bad connection between the alternator and the battery (cable going from alternator to starter then battery) and the ground strap for the engine.
Other possible suspects are the battery (is it old?) and the regulator itself.

Regards,
zp

bobbber · Posted: Wed Jun 30, 2010 8:46 pm Post subject:

Some countries did have "always on" lights on the s2 33

paulhide · Posted: Thu Jul 01, 2010 5:52 am Post subject:

Hi zp, surely if the battery was old it would have difficulties turning the engine (which it doesn't). I've changed the whole alternator to see if there is a difference, but out of interest, which is the regulator? There are two things on the back of the alternator. One attached with one screw and a short lead attached with a spade connector into the alternator OR a larger item attached with two screws (made by Bosch).
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bobbber · Posted: Thu Jul 01, 2010 6:34 am Post subject:

Gritsop has full details here : http://www.alfa-restoration.co.uk/alternator/alternator_rebuild.htm

paulhide · Posted: Thu Jul 01, 2010 2:50 pm Post subject:

Cheers Bobbber, that's quite a full-on overhaul. Very Happy

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ZeNiTh-PbArM · Posted: Thu Jul 01, 2010 10:20 pm Post subject:

Hi, I once saw a battery that would start the car all right, and would go high impedance when hot. After an hour or so the battery light would begin glowing from time to time, and hot restarts were impossible. Replacing the battery solved the problem.
Did the alternator replacement cure your problem?

Regards,
zp