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MG TD TF 1500 - Third Brake Light (LED)

Can an LED third brake light be used on a pos ground system? I'm speaking of a type where the bulbs can not be replaced and built as a unit.
Such as,


Paul S Jennings

LEDs are ground specific, just hook it up correctly and yer good ta go.
MAndrus

So in other words, I hook up the positive wire (red) to ground and black to a hot wire? PJ
Paul S Jennings

I seem to remember something in the archives,,,,
Steve Wincze

Paul, if it has two wires, probably red and black, it can work either way. The red wire will need to go to the positive connection (in your case ground) and the black wire to the signal line. Bud
Bud Krueger

On the TD black is the ground wire (earth) & red is used as the feed to the different lights, with a variety of trace colours. Should be the same on the TF, so if it was me I'd be inclined to maintain black as the earth & red as the feed, that way all black wires remain at earth potential. But that's just me. Cheers
Peter TD 5801
P Hehir

I did the polarity specific LED light on my POS earth TD by simply remembering that the frame (earth) is POS and the signal wire is NEG. To help the next guy Peter's probably right so paint the earth wire black and the NEG wire probably green to be consistent with the brake/turn signal wires. Jud
J K Chapin

Thanks guys. It has 2 wires, one red, one black. I have read many times LEDs are polarity specific and reason for clearing this up. Thanks again, much appreciated. PJ
Paul S Jennings

Just try, nothing breaks when they are connected the wrong way.
Only when there is a metal housing, you need to be careful that it is isolated from the car chassis.

Rgds, Mike
Mike Fritsch

No problem. I ran rear brake lights, turn signals and running lights all as high power polarity specific LEDs on positive ground... just wire carefully!
I had to rewire when I went to negative ground, which I recommend anyway... safer and it makes it easier to use LEDs and modern electronics...
Geoffrey M Baker

I have positive ground and this is a light from a Jeep.
Mort

Mort 50 TD

This thread was discussed between 10/07/2015 and 11/07/2015

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