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MG TD TF 1500 - New electrical part dead short

Yesterday, I did a check of the electrical system in my TD restoration.

Unfortunately, all did not go well. Smoke under the right fender when I turned on the parking light switch.

Damage was to the red wire going to the side light.

I dropped the dash and did not find any damage to the wiring under the dash.

I diagnosed the issue as a dead short in the brand new side light bulb holder. Looks like something went wrong when they put the insulation between the plate and the power tab.

I don't know what supplier I got the bulb holder from.

My recommendation is on any new electrical part you buy, check it with your multimeter to make sure there is not a dead short.

The wire damage appears to only be about 8 inches down from the light. I put 12v to only the wire to that light and check for voltage at the other wires in the loom. I did not find any crossover voltage.





Bruce Cunha

I hope all the bad smoke escaped so you won’t have any issues in the future with smoke escaping.

Regards, Tom
tm peterson

I am trying to understand how that wouldn't short out.

The positive connector plugs into a socket that sits on top of a piece of insulating material, but then is RIVETED to the base plate that is bolted to the fender. So why should I think that those rivets will not conduct electricity?
Christopher Couper

You are correct. The lamp ring (positive ground) is riveted through the insulation and through the bottom plate. The power terminal is riveted through the insulation and there appears to be a strip of paper between it and the base plate.

Only thing I can figure is the power rivets have gone through the paper and are touching the base plate.

Perhaps the machine that puts the paper on was a bit off that day and it did not get both rivets?

Bruce Cunha

Can you drill those rivets out and replace with something that will be acceptable?
Christopher Couper

That is pretty easy to do, and I probably will do that. I do have some original ones that I will be looking over to see if any are good to use.
Bruce Cunha

This thread was discussed between 01/12/2023 and 02/12/2023

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