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MG TD TF 1500 - Lamp, Ignition warning/fuel warning

Is there a difference in the 2 lamps the ignition lamp has a Moss #142-200 and the fuel lamp has #142-210. What is the difference other than the color of the lense? If they are different then this will solve my ignition on light problem.
Thanks;
Louis
Louis Levin

Yes, Louis, the lamps should be different. The low petrol lamp is just a 12v bulb that is either on or off. The ignition lamp is indicating the difference between the battery voltage and the generator output. The socket is constructed with an a mount of resistance wire in series with the bulb.
See http://www.ttalk.info/Tech/Indicators.html for some more information on this. Bud

Bud Krueger (TD10855)

the british parts supplier..can't think of their name now sells them for less than moss..same part number..they provide the lens color of your request. regards, tom
tom peterson

bud, the mg service manual for the TD shows the same bulb for ignition, fuel warning and headlamp beam lights, number 970, a 2.5v and .5watt. don't both lights have a dropping resistor wire on the bulb fixture for the bulb? the TF shows 12v bulbs. regards, tom
tom peterson

Louis,

I simply cleaned up the sockets and bought new lenses. The wire resistance was intact. The sockets looked identical to me, so either I lucked out and used the right socket in the right place, or else they are interchangeable. The bulbs in both sockets are interchangeable too.

warmly,
dave
Dave Braun

MY question is are the sockets different? If so how do I tell which one is for the ignition light? Sorry to be a pest, but I think that may be the reason the light stays on. I have done all the tests that are recommended to fix the light problem, and still shines.
Louis Levin

Louis,

These 2 lamp holders are idemtical, both have a wirewound resistor. The difference in part # in the Moss catalogue is because of the colour of the lense.

John
J Scragg

Mea culpa. Shouldn't have jumped so fast. Yes, ideally the sockets are the same. Only difference should be in the color of the lens. I'd sure like to know what bulb is supplied with the lamps. Bud

Louis, did you ever check to see where your ignition light is connected?
Bud Krueger (TD10855)

Is it possible to rewind the gen light with some type of resistive wire? If so, where can I get the wire and what type to use? Nichrome? Thanks all.
BRIAN WARMUTH

Yes Bud, I have checked everything. I just took one of the extra sockets apart and found that the piece inside the unit is a spring like rod that moves up or down when the current goes through it. Maybe the one I am using is not working correctlly on the inside. I will check it out to see if it moves.
Louis
Louis Levin

Louis, the spring and rod inside are just to make contact with the bulb. The resistance wire is wrapped around the outside of the socket.

Brian, it's much simpler to replace the resistance wire with an external 75ohm/2watt resistor. Bud
Bud Krueger (TD10855)

Little British Car Co. is probably the merchant Tom was referring to.

http://www.lbcarco.com/cgi-bin/gen5?nextform=/mainf.html&o=&a=

The only reason a resistor might be in the circuit (not shown on wiring diagram) would be to dim the bulb (maybe they experienced overheating with long periods with too intense bulb). Personally, I'm throwing LED idiot lights in one dash (7 total).

Louis, is this the subject previously hashed out where the ignition light is on all the time? You have to determine if generator is working first off.
Does ammeter run in the "+" revved up? Do headlights brighten when revving the engine? Does your battery go dead after awhile or can you cruise for hours with no problem?
Stick a volt meter across your battery. Charged up, it should register approximately 12 1/2 volts. When you start your engine, it should jump up in the 13-14 volt range revving the engine. Does it?

If you are absolutely sure your generator and regulator are working right, then you have your ignition light hooked to a wrong terminal or terminals.

That light function is pretty simple: when you first turn the ignition on, the ignition circuit has voltage and so does that bulb. It is only grounded through the generator armature and lights up while the engine is off. Once the engine starts and the generator pumps up voltage, that bulb is no longer grounded since both sides of the bulb are both approximately the same voltage. If the generator is idling and can't crank out enough current and the ammeter runs in the "-" side, the bulb may glow dimly, but nothing like when just turning the key on.

There should be a white wire on one side of that bulb running to the "IG" terminal of the ignition switch, and a yellow wire running to the regulator terminal "D" for Dynamo.

I just strung a new harness in today for one of our TDs and am up to my eyeballs in colored wires and a very complicated dash.
Jim Northrup

jim, when i get back home i will look up the name of the british co i made reference to. they are the out fit that sells all the lucas stuff. jeff at LBCco is who i use for all the Moss stuff. excellent service as everyone here probably knows. regards, tom
tom peterson

Or, it might be Brown and Gammons?
gblawson(gordon- TD27667)

This thread was discussed between 16/06/2010 and 17/06/2010

MG TD TF 1500 index

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