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MG MGB Technical - Warning light on when ignition off

Every so often I've noticed when I've parked up and turned the ignition off that the Red warning light has stayed on.

The last time this happened I started the car again and the temperature and oil gauges looked fine..when I turned it off again the red light wasn't on.

I haven't had any power problems, the clock on my radio would tell me if I had.

What could this be?

Thanks,

James
J Elliott

This has happened to me and I opened the voltage regulator and adjusted the spring pressure and solved my problem. Maybe yours is the same. I guess over time and vibrations the adjustment goes out of wack. Good Luck
Ed Kulick

Hi James

Do you have an alternator or a dynamo ?.

Don
Don

James presumably has an alternator as his is a '78 car.

I've just done the Bosch upgrade and it's great, if you've got a duff alt I recommend it. Mine was payment in trade for half an hour's work, so I think I did quite well out of that one.

ttfn,
--
Olly
Oliver Stephenson

I had this happen one winter and it turned out to be mud caked on the cap of the starter solenoid partially shorting the terminals. Cleaned it out, fitted the missing starter cover, and the problem never returned. Hope yours is this simple!
J Hall

Thanks,

It's still happening.

I'll have to do a bit of investigating..I just wanted to make sure that it wasn't anything more serious.

Yes, I have an alternator.

James
J Elliott

With the engine stopped the alternator is supplying a ground to the warning light so if the light is on 12v must be coming from the ignition, just like when you first turn on the ignition but before the engine starts. At the very least this will be draining the battery but may also be maintaining power to the fuel pump - a very bad thing when parked.

The 78 has the ignition warning light connected to the output of the ignition relay and the coil direct to the ignition switch. The implication is that the ignition relay is sticking on (you can turn the engine off because that is powered off the key, not the relay), so lighting the warning lamp but also powering the pump (and the overdrive circuit). If so I would class this as 'serious'.
Paul Hunt

Hi..

I agree that the replacing the relay is the first thing to try.
If the relay is not the problem, and if the car has suffered the overdrive switch wire short problem, there might be a short in the loom, due to insulation breakdown.

Don
Don

This thread was discussed between 21/01/2003 and 22/01/2003

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