Stop light switch - gone again!

[Baz]

Brake lights didn't work bilateral, tested switch and switch kaput. Replaced switch and brake lights worked for about five pumps then went kaput again, again bilateral.
1. What could make a switch fail so quickly?
2. Would it help if I bypassed the regular wiring harness, and ran the wires straight from the switch to the lights?
This is driving me crazy, beautiful weather, engine great, yet can't drive it!

 

[dklawson]

I don't know when BMC/BL switched brake switch types so forgive this question: Is your switch hydraulic or mechanical on the brake pedal box?

I've had problems with hydraulic brake switches when used on cars converted to DOT-5 fluid. I decided in my Mini to install a mechanical, pedal box mounted switch as was used on later cars and wire it in parallel to the hydraulic switch.

What do you mean the switch failed "bilateral". Is there a chance that you've wired up your normal brake light wires to the "H" shaped pressure-differential-warning switch? If so, that's not the brake light switch, it's only supposed to light up a warning lamp on the dash when there's a problem. It's OFF when everything is OK. There's a separate switch that's supposed to power the brake lights. If it's the PDWA, there have been a couple of other threads about that recently so you may wish to search the forum about it.

 

[Baz]

I tried to add a picture, bit too big. It is a mechanical switch on the end of a thread just forward of the lid for the pedal cover on the starboard side. It did work for a few minutes so I'm somewhat sure I wired it right, all other lights checked OK also at the time.
Is it any coincidence that the flasher is going bad too? It's going bad in a hurry!

This wiring in the trunk has caused me many a problem, the turn lamps were wired to the dual filament on the stop/tail, and brake lights to the amber lens, both the brake lights and tail lights were grn/prp so it was a challenge. The previous switch was very rusty, looked like it had been on the Titanic. Do I need to re-wire this whole back end?

I am entered into a car show on saturday in which I am the only entrant in the 'British Cars' class, so I'm bound to win, even though it's not in the best condition! Ironic that a brake light will stop me from going....

 

[Baz]

The switch is stuck closed yet again. This is getting expensive. Any suggestions on what is causing the switch to fail will be appreciated, I can't keep a stock of them.

 

[Trevor Jessie]

You may be able to take it apart and clean it up. It sounds like some faulty wiring is causing some serious arcing. But that is just a guess. You can fashion a bracket a fit a more reliable micro switch.

 

[jlaird]

What the heck. Check the input to the switch with a volt meter, amp meter. Something is burning them up. Where is all the juice comming from? Coil??

 

[dklawson]

It is curious that the contacts in the switch would get damaged so quickly. It sure sounds like something more, much more/bigger is on that circuit and drawing a lot of current.

 

[Morris]

Are the brake lights fused? I can't remember. If so, is it possible that DPO bypassed the fuse so that a short in the system is pulling major current through and burning the contact.

I have successfully dissassembled my brake switch to clean the contacts. Then I successfully put it back together with a whole tube of JB Weld. (Okay, maybe I didn't do such a good job taking it apart). Anywho, it works good now.

 

[jlaird]

Well if it works it works.

Keep an eye out for smoke from someplace maybe. If you see smoke you have found the problem unless it was just poorly manufactured swithches.

 

[Morris]

There was a thread a while back about the poor quality of the brake switches sold by VB and Moss.

 

[aeronca65t]

I've had two of the Moss mechanical brake light switches fail in my racer and my brother's replaced two in his street Midget as well. My most recent one has been apart for "improvements" too.
They are poorly built (in India, I think).
I am considering a swap to a US or motocycle type switch next Winter.

 

[jlaird]

Aye, I have never seen one of these but would think a replacement something would not be too dificult to find.

 

[Baz]

I'm stumped. No shorts, electrical looks as good as it could for Lucas. Local shop is putting in a switch from an old Jag tomorrow, see how that goes. I'm curious as to an electrical switch.
hand signals are getting old.

 

[regularman]

I replaced mine with an aftermarket one. I had to drill an extra hole in the pedal box but its easy to get at and works good and easy to replace. I used an extar long pin in the brake clevice so it sticks out and presses the switch. I did this a while back and don't recall where I bought the switch, but it was one of the local auto parts chains. $30 for a simple normally open switch just seemd like too big a rip off to me, and to hear that they aren't good quality makes it even worse.

 

[Baz]

Operator error on my part, my apologies and thanks for the suggestions. I screwed it in too tight, and it kept sticking.
All fixed now....Off to the show!

 

[wolfman]

I have worked and worked on these switches. Replacing, rebuilding, nothing any good. Tired of it, installed after market and haven't touched it since.

https://www.watsons-streetworks.com/brake_switches.html