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MG MGB Technical - Ignition Light

I have a 1980 mgb roadster. The ignition light goes on when the keys are taken out hence draining the battery. The light goes out when the key is turned and the engine is running. Any ideas?

Dave Durnell
David Durnell

I had this exact problem with a new 'recon' alternator that I fitted last Christmas. After about 2 months this fault developed and, like you, I had a flat battery the next day. I have no idea why it happens. Perhaps an electronics wizard could explain. However, a replacement alternator cured the problem. I was lucky as I had not sent the 'old' unit back as exchange and could just swop the alternators to trace the source of the problem. The dealer I used had not heard of this problem before but supplied me promptly with an exchange unit and, touch wood, the problem has not resurfaced since.

good luck,

Steve
Steve Coulson

Had the same problem with a '79. Replaced the alternator - someone had told me it appears a diode had gone bad. Problem solved (6 months and counting)

Ed
Ed

Thanks for the responses. It was the alternator. Apparently a diode had blown and the subsequent spill of solder had created the short.
David Durnell

This thread was discussed on 29/11/2001

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.