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MG TD TF 1500 - TD tail lights

noticed when i came home the other night my tail lights and tag light do not work when on headlights setting. they come on with the side lamps but go off on headlight.
bad switch? can it be rebuilt?

Thanks
TLW Wright

Not sure what the problem is but the switch can easily be taken apart & cleaned. Removing it is time consuming & it helps if you're a contortionist. It's a very robust design with little that can fail. Putting it back together is a little more difficult. See my "how to" thread in the archive. Cheers
Peter TD 5801
P Hehir

I would check the tail light ground connection.

Jim B.
JA Benjamin

Will check the ground . Just assumed since I had lighting with the sidelights on, the ground was fine. But good to check the easy stuff first. Could also check for voltage there.

I will look up the switch thread. Not going to happen until it gets colder anyway.

Thanks
TLW Wright

IMHO, if the lights are functioning in one setting the grounds should be fine. It's more likely to be an internal switch issue. Peter's 'how to' thread should allow you to get into the switch. I'm wondering if anyone has any experience with spraying contact cleaner into one of these switches? Bud
Bud Krueger

Before you tear apart the switch, check the voltage at the T terminal in both lighting positions (side and head), If the voltage drops while on the head position, it is likely the switch. HOWEVER, these switches are fairly robust. The main spring inside provides a significant amount of pressure on the contacts, enough to normally overcome any build up of grease or dirt.
It is certainly possible that a bad ground somewhere could cause the symptoms noted, as if the ground is being provided through another component (not the tail lamp ground) or the ground is weak, the drain the headlights impose could drop the voltage to the tail lamps enough to appear to extinguish them.
99% of the time, electrical quirks come down to a bad ground.
LD Palmer

Good test, Lew. I'll be anxious to see what the voltage is in the two conditions. Bud
Bud Krueger

i went back out this evening before reading the info above. after looking at the wiring diagram i noticed the fog lights, the dash lights all work from the same terminal T on the switch so i thought it a good idea to turn out the light in the shop and see what does come on. when i went to headlight position, nothing else was on. as i started to turn it back, i felt a notch half way between the main and side position. when i left the switch there everything came on just fine. So appears to be in the switch. assuming not supposed to work this way...
i tried to do a search of the archives for the switch rebuild but my searching skills are not the best. could use some help with that if anyone knows where it is.
this is definitely a winter job now since i can get everything to come on. have a couple of other winter projects to do then so just adding this one to the list.
TLW Wright

See http://www.ttalk.info/EarlesImages.html for some images from Patick Earles. Bud
Bud Krueger

thanks bud.
TLW Wright

See 'Ignition Switch reconditioning' in 2015 threads. Bud
Bud Krueger

I just had the same problem. Turns out I had the wires in the wrong terminal. Make sure they are in the one marked "T". It's dark up there.


Jim
J Barry

This thread was discussed between 13/07/2015 and 15/07/2015

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.