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MG TD TF 1500 - red ignition light stays on

I just noticed that the thread before me has the same issue. I will still post!


I recently got my 1955 TF registered and on the road for the first time. I noticed right away that the red center ignition light stayed on even as I got up to speed. I will continue to drive and eventually the light will go out but will come on again. I read in the manual that I should not continue to drive the car with the light on. The amp meter seems to be operating correctly where at idle it is slightly negative and as I get up to speed it will continue to rise almost to 30 amps. At 50 mph it will be around 15 amps. I am not sure what is right or normal. So two questions: What is causing the ignition light to be on most of the time and what are typical readings for the amp meter? Thanks!
A.D. Andre de la Chevrotiere

A.D.
Hi, I'm the guy who has the same problem in the other thread! Glad to have your company. These guys must think I'm crazy by now.

I'm still working on it. I also found an old post from 2003 where another guy had this problem. He "resolved" it by "bending a few tabs" on the back of the light, or so he said in his last post. I wouldn't recommend that because the whole thing could fall out and it's a BEAR to put back in - trust me!

Wondering, if you pull the 2 generator leads from your generator like I did and turn the key on, do you also see your light come on dimly? If you can try this please let me know. Make sure the 2 leads are not touching any metal when you do this! Don't start the car, just turn the ignition on. If you don't feel comfortable doing this, please don't! This isn't a test for our common problem, per se, but just a favor for me.

I'll try to keep my thread alive till I resolve this.
Ed

efh Haskell

A.D.
We have a new possible reason for our common problem. By any chance is your warning light new and if so, from whom did you buy it?

Do you have a volt meter with a continuity testor feature? If so, could you check for continuity between either of the 2 terminals on the rear of your warning light behind the dash to the rear of the metal insturment panel? I tested mine and I DO have continuity there and there should NOT be any! The light should be totally isolated from that panel. If not, when the engine revs with enough rpm to generate more voltage than the battery is sending the other way and this unintentional ground exists, the light would come on. That's the theory anyway.
Ed
efh Haskell

To Andre,
That sounds kind of like your voltage regulator is not behaving itself.

When you first start your engine the ammeter should go to "+" as you rev the engine, maybe as high as 30 Amps but in a few minutes of driving it should start to come down. With a good healthy battery it will get down to 3 - 4 amps. If you have an accurate voltmeter, when measuring the voltage across the battery, you should see about 14.4 volts. More than this and you will be boiling the water out of the battery. Less than about 13.8 volts and you will not recharge your battery.

What other questions do you have??
Cheers
Bob
Bob Jeffers

This thread was discussed on 16/05/2012

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