alternator problem?

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pc.blogs
Posts: 5
Joined: 30 Sep 2002, 03:16

alternator problem?

Unread post by pc.blogs »

i have a 96 xantia 1.9td. Is it possible that the alternater could back feed to illuminate warning lights on the dash as i keep getting the glowplug light on when car running(dimly) and also intermittant warning/stop light. Ive been told by a mechanic that the alternator is worn and could be the cause. The symptoms are prolonged when it is wet or raining.
thanks
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AndersDK
Posts: 6060
Joined: 21 Feb 2003, 04:56
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Unread post by AndersDK »

No -
The (running) alternator supplies a +12V feed to the charge lamp, which is connected to the battery +12V inside instrument. Thus the charge lamp extinguish when alternator is running, as the lamp then gets +12V both sides.
It is much more likely you have a mess (corrosion) in the glowplug timer wiring - or the earth connections under the battery which are exposed to battery (acid) spillage.
jeremy
Posts: 3959
Joined: 20 Oct 2002, 16:00
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Unread post by jeremy »

i agree Anders. I had my alternator overcharge on my BX TD and apart from a great improvement in the headlights and frantic wipers I noticed little else - certainly not warning lights misbehaving.
I would start by measuring the voltage accross the earths etc (there shouldn't be very much of a reading between the battery negative and the engine block) and investigating any readings - ie clean terminals etc.
I suppose its also possible that there is an earth problem on the instrument panel - perhaps one of the plugs has come loose or corroded. What happens is that without an earth the circuits will look for anything at a lower potential.
jeremy