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MG TD TF 1500 - Halogen bulbs need relay?

I did a search and found nothing definitive on whether or not I can fit rear halogen bulbs for the brake/rear lights. Does this upgrade require a relay or some other nefarious electrical work?

Thanks again as always! This board is great!

Best regards,

dave lackey


Modern lights need modern wiring. If you're still using the original wiring harness, you're taking a risk by running a high current device on this old harness. I wouldn't do it.

A few years ago, I replaced my headlamps with the Sylvania Silver Star sealed beams. Great lamps, but I'm sure I'm pushing the wiring to its limit.

Have a gander at Bud Kruger's web-site "T-Talk" -

I'm sure you'll find what you need in there to re-wire for high current devices.

Gord Clark
Rockburn, Qu.

Gordon A. Clark

Dave - Before converting to the halagon bulbs, look at the power consumed by each filiment as compared to the original bulbs. Some of the halagon bulbs use a considerable amount of power while others don't use any more than the original bulbs. I would suggest putting a relay/arc suppression circuit in the brake light circuit regardles of which bulb you use, to insure that the brake light switch does not start giving you problems. For a relay/arc suppression circuit that you can make and install, see my article at:

Gord - You can reas easy about the Sylvania Silver Star sealed beams, I checked the current draw on them before sticking a set in our MGB and found that they draw the same amount of current as standard sealed beam head lights. Cheers - Dave
David DuBois

hello, for the tail light/brake lights have you considered LED'S ? regards, tom
tm peterson

I think Dave is talking about brake lights. My car has them, I believe, with the original wiring (no relays) and they work fine and are very bright. My car also has them with the front side lights, which are also great. I think they draw much less power than headlamps.

Regarding halogen headlamps, I bought them from Moss, turned out to be wagner/sylvania and they draw the same current as the original bulbs (roughly) I am using them with the original wiring loom (getting old and cracked) and so far have had no problems.

Larry Ayres

Tom Peterson, where did you find LED's that work with the MG ground system? I have been searching for LED 1157s but they do not work with the original grounding of the car. Something about the current in an led bulb.
Tom Maine

One of the TC owners in our club had someone 'make up' positive ground leds....sounds like it is something an electronic shop (?) can do?
Also found them with a search on the web...forget now where they showed up.
gblawson - TD#27667

For those with negative ground systems, go here for LED 1157s. I have bought bulbs from them before, but not their LEDs.
L Karpman

hello tom, i will post the LED info. it will take me a bit to dig it up. regards, tom
tm peterson

This thread was discussed between 05/09/2006 and 06/09/2006

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