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MG TD TF 1500 - Easy question - brake lights

My car ('50 TD) is back on the road, but I'm still tackling a few issues between jaunts around the neighborhood in the evenings (I really admire you guys who venture out on the expressways in these cars...I remember driving this car to Atlanta once as a teenager and swore, "Never Again!", that was 30 yrs. ago).

At any rate, My brake lights don't work and I'm pretty sure it's the switch that's under the driver's side in the brake fluid line (I didn't replace this piece during the restoration, but have a new one on the way). The tail lights work fine, just nothing when I apply the brakes.

Question 1: should the brake lights work even when the ignition switch is off?

Question 2: when I pull the switch off, will brake fluid come pouring out?

The brake lights only work with the key on...

The switch faces down but very little fluid drips out and doesn't even need rebleeding (as long as no one steps on the brake...
I have gone through 3 of Moss's (or any of the new ones) brake switches...I ordered one of Dave DuBois' little brake relays and it has been trouble free for over a year.

good luck
gblawson - TD#27667

Try the brake switch with a trouble light. If you have turn signals, your trouble may well be in the turn signal relay. Hopefully, it is the switch as the relay may not be repairable and is expensive to replace.
David Werblow

Thanks David, no turn signals on this one (except my left arm, which is the one part of the electrical system that seems to be working lately). I did try a test light and got juice on the front end of the switch but nothing after the switch.

If I had an extra hand I wouldn't hesitate to put a manual brake light switch somewhere on the dashboard (I've used the tail lamps a time or two during the day on my recent test drives to alert the tailgating driver behind me that this jaloppy was coming to a halt). But, between holding the two doors shut, shifting gears, holding my hat on, and keeping a hand or knee on the steering wheel...I'd be all out of limbs to push a manual brake light switch! :-)

Get a new switch from NAPA and one of Dave Dubois' relays and you'll be fine for a long time.


Larry Karpman

Robert - Everybody says to get one of my brake light switch relay/arc suppression circuits, so I guess that it may be working for others as it has for me. The problem with the brake light switches is that the Lucas switches were so very reliable (how's that for a change up?) that we just assume that they are going to worki forever. Unfortunately, after many years of faithful services, these switches (like all things electro-mechanical) finally wear out and that is where the trouble starts. When one goes out and purchases a replacement switch, they expect that it is going to work for as long (if not longer - after all it must be state of the art in this day an dage of high tech). Alas, this is not the case, we may be high tech dow days, but we are also after quick and high profits so what is produced is a light duty switch that is barely sufficient for a flashlight (I had one burn out in only two weeks). My approach to all of this was to make up a relay and arc suppression circuit so that all of the current for the brake lights is handled by the relay and the arc suppression circuit eliminates any arcing at the switch contacts. When you install the new brake light switch, you need to install this circuit to make the switch last (or you can order the super heavy duty, super expensive switch sold by the Ron Francis Wire company at:, I am told that these switches hold up very well). If you are handy with a soldering iron, you can make up the circuit yourself by getting the instructions at:
Or I can supply one for you if you will contact me by e-mail. Cheers - Dave
David DuBois

Dave, guess what doesn't work on the Wolseley... here we go again!!!
gblawson - TD#27667

Gordon - "guess what doesn't work on the Wolseley... here we go again!!!" I'm sure it is exactly the same switch as in the MGs. Cheers - Dave
David DuBois

Robert, see for an
approach to adding the relay.
Bud Krueger

If you're looking to replace the brake light switch, NAPA can supply the Echlin for about $12. Echlin SL144 for screw connections, SL147 for the blade terminations.

Gord Clark
Rockburn, Qué.
Gordon A. Clark

I agree that the idea of adding a relay is an excellent one and I promised myself to do it - as I have done for the horn with that awful horn switch. However, I have been too lazy to do it and I have never had any problem with just the brake switch. Maybe we don't brake down here!

Denis L Baggi

Good thing there are no 'hills' in Switzerland!!!!
gblawson - TD#27667

Denis - You may well have an original brake light switch in your car. If you do, it may well outlast you. Cheers - Dave
David DuBois

Thank you Dave. In fact I do, I never changed it, and I bought the car in 1965.

However, if you feel like, please tell me what has changed since then, so that if I have to replace it I will put that relay. Actually, I have a replacement that came from another 1950 TD!

Thanks for your comment, Denis
Denis L Baggi

Denis - "if you feel like, please tell me what has changed since then," The switches today are made a cheaply as possible and are very lght duty. If you look at the picture below, you will see that the movable contact of the switch does not have an actual contact on it, just a piese of very thin spring bronze that has become discolored ftom the heat of the current carried by it after only a fwe months in operation. In all fairness, I am sure that the manfactures are doing this in an effort to keep the cost down, but the result is a switch that will not last more than a few months in operation. There are some high quality switches (although I cannot comment on them from a personal experience, because I have never used one) on the market, but they are quite expensive. The Ron Francis Wiring Company, carries such a switch. Cheers - Dave

David DuBois

Thank you David, what you write makes a lot of sense and I'll keep it in mind, should I ever have to replace the switch.

Denis L Baggi

This thread was discussed between 01/08/2007 and 06/08/2007

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