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MG MGB Technical - 73 B ignition light on

it's a 73 B, totally unchanged from the factory and has its ignition light on only when the car is off and the ignition in off position
Anyway have the likely cause?
F Ost

That happened to me once with my 71. Coming out of winter storage I connected the battery backwards. By the time I noticed it I had turned the ignition on and blew the diodes in the alternator. Won't do that again.
G Nicholas

thanks, it's the same battery, never disconnected, but alt is not charging so I'll start there
F Ost

Sounds like a shorted diode. Time for an alternator.

"it's a 73 B, totally unchanged from the factory"


"it's the same battery, never disconnected"


Any road up, does sound like alternator diodes. You can get replacement diode packs, although if it's not charging at all there could be something else wrong as well.

"Any road up"!!!! You'll soon be extolling the virtues of flat caps, mufflers, whippets and clogs and going up't ginnel if t'weather's owt bit like!!
Allan Reeling

Got the first two :o)

This thread was discussed between 20/07/2016 and 24/07/2016

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