MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Brake lights don't work...likely the relay?

Guys:

Just love spring...time to find out what isn't working....this time it's the brake lights. I suspect it's the brake relay since the running lights and turn signals work...but nothing when I depress the brake pedal. I researched the archives so I'm pretty sure a replacement relay is in order. However, might there be any other reason why they are not working? Also, I saw reference to a relay that can be purchased from NAPA Auto Parts that apparently can be screwed into place on bottom of the 4 way valve. Any installation tips or advice is always appreciated.

Thanks!

Jim
Jim Rice

Jim - Unless somebody installed a relay dedicated to the brake lights, there is one on the car. I think that the relay you are referring to is the turn signal relay, which the brake lights are routed through. No turn signals? Then there is no relay. I suspect that the problem with your brake lights is the brake light switch - they do wear out over many years (or many days in the case of today's replacement switches).

You can get a new brake light switch at NAPA (ask for a switch for a 65 MGB - same switch), or you can purchase a very expensive one from Ron Francis Wiring - http://www.ronfrancis.com/ that will last somewhat longer. My suggestion would be to get the cheap switch from NAPA and make up a brake light relay as detailed in the article, Brake Light Relay in the other Tech Articles section of my Homepage at: http://homepages.donobi.net/sufuelpumps/ I can also make one up for you for $18.00 including postage. Cheers - Dave
D W DuBois

I like to keep things simple so went with the Ron Francis stop lamp switch for a number of my cars and have had no problems since.
John Quilter (TD8986)

I'm confused too... there was no relay for the brake lights, was there?
Geoffrey M Baker

The last one I purchased from NAPA worked...however...it required near lockup braking to function. Replaced it with a Moss unit I had on hand and all was well when it went to it's new owner.
MG LaVerne

Geoffrey - "I'm confused too... there was no relay for the brake lights, was there?"
The later TD (Late 52 - 53) that had turn signals have a relay to switch the brake light on the side that is signaling to flash with the front light. When the turn signal is turned off, the relay reconnects the rear brake light to the brake light switch.

The brake light relay is one that someone (like me) puts in the brake light circuit to take the high current of the light bulbs through the relay contacts rather than the brake light switch. Practically all the brake light switches (either hydraulic activated or mechanical) have such light duty contacts that they start burning almost immediately upon the first use. The experience that LaVerne talks about ..."required near lockup braking to function" is classical symptoms of the problem. The only switch that has proven to be immune to the problem has been the one sold by Ron Francis Wiring and I am even hearing of some incidents of them failing prematurely. Cheers - Dave
D W DuBois

Jim,
Your original question about >>Any installation tips or advice is always appreciated.<<
It's relativly simple,, first clean/wipe all the pipes that connect to the SWITCH, then unscrew the old SWITCH and screw in the new SWITCH.
IMHO, preferably the one from Ron Francis. You shouldn't lose any brake fluid if it's done without wasting time.

Steve

Steve Wincze

Jim, first thing to remember is that the ignition switch must be turned for the brake lights to work. I'd suggest that you heed Dave DuBois' suggestion about the relay. More at http://www.ttalk.info/Tech/BrakeLightRelay.htm Hard to beat Dave's $18 package. Bud
Bud Krueger

I have Daves relay and it's not only easy to hook up, but works very well. I'd strongly recommend it. PJ
Paul S Jennings

Remove the wires from the brake light switch and touch together- if lights then bad switch. Or easier- carefully short across the terminals with a screwdriver (don't touch the frame or metal). George
George Butz

I replaced mine about 2 years ago with the Moss switch and it's still working well. I thought all the break fluid would pour out when I unscrewed the switch but the installation was dripless. If I had it to do over again (I'm sure I will) I'd put bullet connectors on the wires so I could screw in the switch with short leads attached and then connect the wires going in and out. Right now I have a wad of wires coiled up as many times as it took to screw the switch in.

Jud
J K Chapin

Thanks guys:

To be correct.....I was referring to the brake light switch not a relay.

Dave:

Looks like I'll be ordering your "kit" so to speak. I still need to get a replacement switch regardless I assume?

Bud:

Yeah....the engine was running when I tried the brakes..no luck there.

Cheers!

Jim
Jim Rice

This thread was discussed on 16/03/2015

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now