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MG TD TF 1500 - ignition light dim all the time

Hello,
My car has a new wiring loom (1 year ago), and about 6 months ago I had the generator rebuilt, and the armature rewound. The car has been slow turning over in the mornings (acting like a flat spot on the starter) and now the ignition light is on dimly all of the time.

I have some more tests to make, like generator output, etc and a good ground to the engine, but would the battery failing (it is 5 or more years old) cause these symptoms? I don't remember a bad battery causing the red light to come on, but you never know.

The ammeter also shows no charge, but not a significant discharge when running with the lights off. Its right at zero. It has just reached the point of not having enough power to turn the engine, so I have to deal with it.

I think I will pull the battery and have it tested and charged if ok, while checking everything else.

thanks,
Larry
L Ayres

Larry - the battery should read about 12.5volts after sitting sitting over night. If it reads lower, you probably need a new battery. To test the generator, see the article, Testing A Dynamo/Generator in the Other Tech Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ If the generator tests good, but the regulator doesn't, follow the instructions of checking with Bob Jeffers for his magic solid state regulator conversion.

If the generator tests bad, you will need to get it fixed, but I'm not sure I would go back to the same place as before. If you were not getting 20 volts out of the generator in the test above, and the shop tries to tell you that the generator is good, I would definitely go to another shop (in fact I did just that when I was in the same situation and found that there was a low resistance short to ground in one of the terminals on the generator end plate - the voltage would barely hit 12 volts when the generator was reved to the point of almost coming apart and the shop said "see, it puts out 12V"). If the armature is still bad, you can get a new armature ery reasonably from the Holcombe Armature Co. 800-241-3027. Cheers - Dave
David DuBois

Larry,
I have had the same trouble last year and I changed to Bob Jeffers magic solid state regulator and I'm very pleased with the result. I can recommend this solution.
Good luck
Guenter
Guenter

Larry,

Before changing the voltage regulator, try polarizing the dynamo.

John
J Scragg

More to the point, disconnect the wires from the dynamo. Put a jumper between the two generator terminals, and a voltmeter to chassis. Start the engine (with jumper cables to another car if neccesary). Rev to about 1800 RPM's the voltmeter should read 20 or a little over volts. If it does the problem is not in the generator ( well sticking brushes might limit the current capability).

If it passes the above test and still behaves as you described above, the regulator has probably given up the ghost. The procedure in the shop manual if followed carefully by a very pacient operator should get it to operate after a fashion.
R. K. Jeffers

This thread was discussed on 06/11/2009

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