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MG MGB Technical - Alternator indicator light non-functional

Hello,

I tried to solve that problem and I know it is not a burned bulb and it does not appears to be a bad connection. Any ideas what could cause the problem?

Thanks all,

Jean G.
Jean Guy Catford

I forgot to mention alternator is charging correctly with 13.5V
Jean Guy Catford

Have you measured the voltages at either side of the bulb?
Dave O'Neill 2

With the ignition on, and the wires unplugged from the alternator, earth the *brown/yellow* (NOT the brown!) wire in the plug and the warning light should glow. If it does then the problem is in the alternator.

If it doesn't check the voltages as Dave says. With the ignition on, and the alternator wires still unplugged, there should be 12v at the white, and if the bulb is in the holder it should be on the brown/yellow as well.

If not on the white then there is a break in the white back towards the ignition switch, precisely where it picks it up the 12v depends on the year.

If the 12v doesn't appear on the brown/yellow with the bulb in then either the bulb is faulty or it isn't making contact with both terminals in the holder.

If you have 12v on the brown/yellow, then earth it, and the bulb should light.

If it does, then there is a break in the brown/yellow leading to the alternator plug.

If it doesn't, and you have used a voltmeter rather than a test-lamp, then there is a *high-resistance* connection going back through the bulb and the white to the ignition switch, rather than a complete break.
PaulH Solihull

Thank you for your help guys,

Paul I will do test you suggested

Cheers,

Jean G.
Jean Guy Catford

Hello,

Finally this W.E. morning a mystery was solve. It was a double conector in dash who was discombobulated. A surpise as it is almost new with only 27 years.

Paul extra thanks for your didactic approach.

Cheers,

Jean G.
Jean Guy Catford

Hmmm:

"The term "didactic" is also used as a criticism for work that appears to be overly burdened with instructive, factual, or otherwise educational information, ..."
PaulH Solihull

Interesting Paul:

Signification is in the eyes of the beholder




Jean Guy Catford

This thread was discussed between 21/08/2010 and 31/08/2010

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