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MG Midget and Sprite Technical - 75 Ignition warning light

Problem just started tonight on a drive.
The warning light comes on above idle and as I drove it slowly came on brighter.
2 hours later on my drive back it stayed on bright at all times, while running.
I have a voltmeter gage and when at idle it would read 12-12.5 volts but as soon as you went above idle, the voltage increases until it pegs at 16 volts and the lamp is bright.
Is this and indication of a bad alternator or loose wiring?
RC Bishop

It's always a good idea to check alternator wiring, incl how well earthed; check volts from alternator battery to battery -ve, for example.

16v looks on the high side.

Anthony Cutler

Sounds like the regulator inside the alternator is duff. Check as Ant has described but get ready for a new alternator or a brush/reg pack if you can change it at the rear of the alternator.
Robert (Bob) Midget Turbo

I've had the same problem very recently, also with lamp and gauge installed, in my 1500. Gauge was showing intermittent voltage up to 15.9V, with lamp on until settling in at about 14.4V. Lamp began to flicker at ~15.1V then stayed bright at any voltage above that.

I had assumed failing alternator, BUT then found the connection at ALT from BAT nearly broken clean off. Made the repair a few days ago, have been out for 2 or 3 decent runs, no sign of either high V or lamp on yet.

Also, my alternator is a 3-months new (rebuilt) unit JUST INSTALLED AFTER NOTICING THE ABOVE SYMPTOMS 3 MONTHS AGO.

Richard Reeves

Just check alt by puting an Ampmeter between alt out and to battery and showed no current being produced.
Am going to get a new alternator as check all the wiring and looked good.
RC Bishop

This thread was discussed on 17/07/2010

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