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MG TD TF 1500 - Ingnition lamp

Trying to remedy a non-functioning ignition lamp (a.k.a. "charging lamp").
I have 2 questions I hope someone can answer.
1. What bulb (available in the U.S.) does this take?
2. Is there supposed to be resistance wire wrapped around the base and where does it get soldered?
Thanks in advance.

John - There were two different bulbs used in the ignition warning lamp. The first was a 2.2 volt bulb, US P/N 223 or 233. The sockets that use the 2.2 volt bulb have a resistance wire wrapped around them for the ground side of the bulb. As far as where it gets soldered is quite hard to explain and even harder to solder if it is loose. The wire is a nichrome resistance wire that will not take solder of any kind and probably why the second bulb was used, which is a 12 volt bulb, US P/N 1446.

If I have one of the sockets with the resistance wire on it, I'll take some pictures and send them to you. Cheers - Dave
David DuBois


Either your wires are disconnected, your bulb is burnt out or there's an open somewhere in between.

1. An incandescent 12V bulb will work well if it fits. The gen. puts out about 10V at idle, and will get pretty dim at idle. It should go out completely once the regulator kicks in a charge with a few more revs.

2. Dudn't need wire wrap.

I went to LEDs on dash. That was a nightmare for the ignition lamp since the LED stayed really bright. Went to 24V LED in hopes that it would dim at 10V... not really. I finally used shrink tube on that 24V LED about a 1/2" from the bezel. It gives an interesting indication of discharge/charge.

Don't recommend going LED route unless you have a bunch of time to spend experimenting. I can talk more with you at the next MI NEMGTR meeting in a few weeks.

Jim Northrup

John, see for bit more on the topic. m Bud
Bud Krueger (TD10855)

I have a related question: Is there any harm in eliminating the wire from the ignition switch to the ignition light? I know the light will not illuminate, but I can't see it anyway on my TF and the wire shorted out because the threads on the plastice red piece stripped and the bulb holder came off. I don't want a fire and, as I said, I can't see the ignition light anyway.
Ron Coates

Ron, unlike the MGB system, the ignition lamp is not part of the charging system. It's strictly informational. IMHO, it provides good information and should be operational. Bud
Bud Krueger (TD10855)

Thank you all!
>Bud, your info, like usual, is the place I should look first before posting a question!
>Jim, my crank came in. It's a work of art! Over in Jackson getting balanced this week.


Bud, what information does the ingnition light tell you that the ammeter doesn't? I appreciate your input. Ron
Ron Coates

Ron, I would say that it catches one's attention to things like leaving the ignition switched on better than the meter deflection does. No doubt, there's much more information to be obtained from the ammeter than from the lamp, but you have to be looking at it. You might think of the petrol warning lamp versus the wooden fuel measuring stick. Bud
Bud Krueger (TD10855)

I agree with Bud. Get the ignition lamp working. The TF plastic lenses are available for a buck or two. I am 5'9" and can see my center igintion light well. Maybe you are a tall dude.
It would not be difficult to switch locations and put the useless turn signal light in the center position, and the ignition near the steering wheel where you can see it.
And....yes, you could have a dash fire if those bulb holders are flailing around behind the dash. My vote: fix 'em.
If you need information on which holders need grounding and which don't, email me. Glad to help.

'54 TF
Tom Norby

john, you know..if you don't fix it you will be the DPO for the next care taker who will be scratching his head trying to figure out why you did what you did to a 60 year old car...LOL! or when you go to sell it the prospective buyer asks as he is walking out the door, "what else doesn't work on this car?" regards, tom
tom peterson

I replaced the colored 'jewels' on all three warning lights about 10 years ago. The turn signal one came loose a year or two ago and now the iginition one. The threads on the jewels were shot. I cannot imagine why they threads were stripped unless I did it when I installed them. The ignition one coming loose is a problem when driving. I had smoke from under the dash and I pulled over and found the wire with the bulb holder and bulb hanging down. I didn't discover the wire from the ignition until later and the insulation was completely burned away. I don't know why it didn't blow a fuse, but I thought I would not replace it so that I wouldn't get a fire the next time the jewel failed. I can't see it because the black foam trim on the dash covers it. I guess it must be too thick.
Ron Coates

Another result of a long-term restoration and deteriorating memory. I see on my assembled dashboard - sitting elegantly in my library - that I have the red and green (ignition and fuel) lamps in the wrong positions. I'm now not sure if I replaced the new lenses on the wrong socket or switched the sockets. The sockets are similar but one has bare wire windings part way down the base and the other covered windings all the way down. Are these sockets interchangeable and it's just a lens switch or are they use specific?

Thank you in advance for any advice.
W Worden

looking at the Moss Catalog I believe the sockets are the same for red or green.
If the wires are bare its not a good thing. That is a resistance wire and shorting will lead to a lower resistance and a brighter light.
I would paint the exposed wire Glyptol or some such insulating enamel. Also on the TD the sockets an wires should be ultimately be covered with a "tape". Originally a red cloth tape.
I used a red cloth backed duct tape.

Before assemblying, check to be sure tat the resistance wire is continuous. If broken you will not be able to solder but I made some crimps.

Jim B.

JA Benjamin

See for some info on the lights. Bud
Bud Krueger

This thread was discussed between 26/03/2011 and 16/02/2019

MG TD TF 1500 index

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