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Vauxhall Vectra and the case of the iompossible alternator

Hi All,

I have a problem with the alternator charge warning light on my 2.0 petrol

1997 Vauxhall Vectra.

Recently, the car gave the usual symptoms of an overcharging alternator, i.e. blew the warning light, heated screen refused to work, all instruments packed up above a certain RPM. Alternator was putting out as much as 17.5 volts as the revs increased. Good job I don't usually rev it much!

The Alternator has been replaced, and the faults have all gone away, except that the warning light does not come on at all. Have checked voltages across battery, and all appears to be charging properly.

How can this be? I thought that without a voltage via the red warning light, the alternator would not have an excitation field to begin generating?

The bulb has been checked, and was supposed to be ok. Has been changed anyway, but does not light up at all.

What am I missing? Does anyone have any suggestions. My local garage had heard about problems with a charging relay, but this appears to be on the diesel only.

Reply to
Mark Williamson
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There's sometimes enough magnetism left in the coils to self excite (sounds a bit rude ;-) ) the alternator. It does wear off after a while.

You're gonna have to chase the wiring/connections from the alternator to the light then.

John

Reply to
John Greystrong

~& isn't there a resistor wired in parallel with the bulb anyway.

Reply to
Duncan Wood

If you remove the warning light connection at the alternator and earth it with the ignition on it should light.

Reply to
Dave Plowman

It's nice if they have done it this way - but lots of vehicles don't, and stop charging when the bulb blows.

Reply to
Bob Davis

instruments

I have known printed circuit board tracks on the back of the instrument cluster to overheat and break under alternator fault conditions. Often they go on the parts of the PCB tucked under lugs on the cluster, so you cannot immediately see the problem. There are also components on the PCB that look like resistors but are actually zero-ohm links that can burn out or go open circuit.

HTH

Anthony Remove eight from email to reply.

Reply to
Anthony Britt

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