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MG Midget and Sprite Technical - 76 midget 1500 charging (alt) issues

While I restore my MGB I couldn't resist the lure of a 76 midget to keep myself in the MG driving seat.
After having a clutch problem (turned out to be hydraulic thankfully) I started to pay more attention to the car instead of blindly enjoying it and noticed my Ign light was flickering and glowing.

Off came the alternator and I took it to be tested, fearing the brushes or so, apparently it checked out fine.

So began my wiring tests. It's a simple circuit but i'm having trouble identifying all possible connections and routings of the wires.
My Haynes manual shows a 2 pin alt for that year, but mine is clearly 3 pin (2 large and 1 small for the light circuit) which more closely matches the later wiring diagrams which I found on the net (a 78 USA one to be exact).

I've had a look at and a replace of a few connectors on the ign switch, battery, solenoid and on the back of the alternator and done some continuity tests on the big wires in the engine bay. I haven't fully checked the engine earth strap yet, but it fires up and runs fine so surely it couldn't be so bad as to cause the charge light to glow and flicker?

It's like a dodgy connection or a high resistance someplace as it goes very dim over 2000 revs and bumps and such cause it to flicker whilst never quite going out.

I'm really not wanting to start cutting into the loom to look for wire breaks for obvious reasons, so advice or help is much appreciated, thanks!
RoadWarrior

let me have your email address and I will send you the right diagram for your alternator
Nick Sayle

Thanks, it's:
sn(four)ke(three)yes@yahoo.co.uk

Replace the (number) with the key number, such as 4. Just as an anti-spam precaution!
RoadWarrior

Just a quick update for archives sake, it infact did turn out to be the alternator, which I suspected all along...

A 2nd test on a friends equipment revealed a diode error.

I'd still appreciate that diagram!
RoadWarrior

This thread was discussed between 06/06/2010 and 08/06/2010

MG Midget and Sprite Technical index

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