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MG TD TF 1500 - A new electrical issue

So after the dead short in the running light, I set up my 12v power supply to check all the electrical system.

When I hooked my multimeter to the head lights, I found I had voltage on each side of the headlight.

Moving the dipper switch did not change it. If I ran it as it is, I would have both filaments (high and low beam) at the same time.

I checked all the wires on the dip switch and all the wires are correct.(the switch was rebuilt a few years back when I was starting my restoration.)

I put in a call to the rebuilder. Hoping I hear something on monday. Oh well, just another bump in the road.
Bruce Cunha

Is the headlight bulb in the circuit? If it is, then remove it and test again.

Lonnie
TF681
TF7211
LM Cook

it looks as if you have the dip wire on the correct lamp terminal but the main and earth transposed.
Switched to main the main would light,switched to dip high and dip would be in series pulling a high load.
I have learned not to trust colour markings but ring every wire to confirm.
I know this problem can occur in sealed beams not sure about earthing on separate bulb/reflector
Ray TF 2884
Ray Lee

Thanks Ray. I am going to pull it out this week and open it up. It is a pretty simple switch so I can see if it is internal, or as you suggest, a wire in the wrong place.
Bruce Cunha

I would suggest you check the wiring first.
Unless you have three hands the TD combined dip and horn switch is a nightmare.
Disconnect both sides to prevent crossover power and check when and which lines have power.
Ray TF2884
Ray Lee

Bruce, it almost sounds as if one of your headlamp lines may be connected to the sidelamp circuit. Any chance of that? Bud
Bud Krueger

This thread was discussed between 03/12/2023 and 05/12/2023

MG TD TF 1500 index

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