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MG Midget and Sprite Technical - Ignition light on

Hi Guys (Gals)
My ignution light's constantly on at the moment. Ran it a few blocks the other night when I noticed it. Been running it 50 miles three times a week all spring/summer and last few years as well with no ignition worries. Car starts and runs well but I'm not taking it to work Monday! Any advice as to what I should look at first? Thanks

Mike T
Mike Taylor

For UK cars ignition light on means:

broken fan belt (so you'd have overheated when you stopped)

alternator/dynamo faulty or not working (battery will run down as it's getting no charge)

Diode(?) in alternator faulty (possibly)

or - poor third (thinnest) wire connection on alternator plug to alternator

plug has three wires one thick, one meduim, one thinner - the one that goes back to red ignition light

that's for UK cars mind
Nigel Atkins

&9 car will have an alternator

If the fan belt was broken the engine ould overheat no matter what, the water pump will stop.

Normally this is a sign of the alternator faulty and normally that is due to brushes worn out. Some alternators have removable regulator and brush packs.
Robert (Bob) Midget Turbo

Mike. I agree with Bob that the alternator would be the first thing to check out. Take a volt meter reading on the battery terminals--that will tell you your basic battery voltage. Should be 12.5V to 13.0V on a fully charged battery. If you have been running on the battery, it will be lower and the battery should be charged.

Next, start the car and take a voltage reading at the battery terminal clamps. This is the running systems voltage and should be between 13.5 and 14.5 volts. If you see the same reading as the basic battery voltage your alternator is not charging the battery.

If you see the proper running system voltage your alternator is charging and there is a problem with the indicator light wiring.

Les
Les Bengtson

3rd or 4th the above

Prop
Prop

x5...just recently went through it, test the altenator.
Dave Rhine ('78 1500)


Do any of the alternator wires fit loosely (barely hanging on?). My light came on and it turned out to be a loose fitting spade connector. I mashed the spade connector's clamping ridges down slightly to get a tighter fit. Problem solved.
JM Morris

Sorry Mike and Bob of course the "when you stopped" was meant to be "before you stopped" but my brain had one of its little snoozes and stopped communicating with my typing finger

I have to be very careful some times as my brain switches off for typing the word not or don't which of course if I missed on reading it back would entirely flip what I written

/Dynamo was for anyone reading with the earlier cars

I only put in my general remarks to give Mike a start as the thread was bare knowning you lads would be along at sometime with mucher more exact advice

Reread this twice, it seems OK (hopefully), I'm not use to this 5 mins only to edit, it takes me ages to spot my typos and missing words

a very short and precise answer from Prop, must be busy watching and rewatching a recording of a certain soccer match
Nigel Atkins

Thanksguys,

Checked the connection-seems good, took a fair bit of wiggling to remove it at least. Got my hands on a borrowed meter. Reading at the battery posts was 12. Started the car, turned on the lights-headlights on high beam and let it idle for 15 minutes. Still read 12 at the posts after that......

Mike
Mike Taylor

Yep good battery then! but faulty alternator!
Bob Turbo Midget England

This thread was discussed between 13/06/2010 and 14/06/2010

MG Midget and Sprite Technical index

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