Brake light switch stuck in ON position - [FIXED]

Post by **Bluesman** » Sun Sep 16, 2007 9:17 am

Guys, among all the small things that need fixing on the -60 2-door the turn has now come to the brake lights which are ON at all times.

After metering the voltages into and out of the thing, I measured the resistance across it. Zero ohms=full short. The funny thing is that even with the M/C out of the vehicle, the brake lights were ON.

(Disconnecting one of the terminals made the lights go off, so no funny mis-wiring in this case.)

Apart from the backwards logic (things that break normally STOP functioning, this item works ALL THE TIME and is therefore broken

) - is there a way to trick the switch back into normal behaviour, or is it replacement time?

Cheers /Richard

Post by **Orkney** » Sun Sep 16, 2007 9:22 am

Dont these work on residual pressure ? and if so could indicate MC problems?

Post by **alex_holden** » Sun Sep 16, 2007 9:26 am

I think you're going to have to replace the switch. It won't be a hydraulic problem if it was stuck on even with the master cylinder removed.

Post by **bmcecosse** » Sun Sep 16, 2007 12:04 pm

Yep - sounds like stuck switch.

Post by **MoggyTech** » Sun Sep 16, 2007 1:53 pm

Be aware the 'New' replacement switches are not very good quality. The next time I have one fail, I'm going to fit a mechanical micro switch at the brake pedal.

If the faulty one has been in there for some time, it could be a pig to get out, without wrecking the brake pipes going into the T piece.

Post by **alex_holden** » Sun Sep 16, 2007 2:03 pm

MoggyTech wrote:Be aware the 'New' replacement switches are not very good quality. The next time I have one fail, I'm going to fit a mechanical micro switch at the brake pedal.

This tip talks about a possible alternative...

Post by **Bluesman** » Sun Sep 16, 2007 2:12 pm

Tnx for the warning. Just another thing to be careful about when replacing. I find most of the engineering "solutions" in this car being very far from "best practice", even if they were state of the art back then. This switch - it´s location and general/pricipal function is a strange beast. It being non-servieceable is also contradictory to the rest of the construction.

Logically, it´s a disaster, just as the oil pressure warning light is GREEN.
I mean...if you suddenly have BAD (or NONE at all) brake pressure, you´d LOVE people behind you at least knowing you are TRYING to apply the brakes. Strange "feature".

Ah well...that postwar engineering inheritage...

/Richard

Post by **Orkney** » Sun Sep 16, 2007 3:11 pm

even if they were state of the art back then

It being non-servieceable

Yeah but bet even the designers never thought some mad bloke in sweden would be needing to fix it in 30 or 40 years

Post by **Bluesman** » Mon Sep 17, 2007 8:12 pm

Fixed. But...the new switch is a disaster waiting to happen. Mixing materials in the electrical contact area (copper and some plated brass), and having the switch exposed like that is doomed to fail. No wonder some of you had to change it often. Galvanic corrosion is bound to happen, especially in areas with road salt. Oh well, guess it keeps the suppliers happy...

Post by **alex_holden** » Mon Sep 17, 2007 8:33 pm

The original ones lasted for decades. It's only the modern pattern replacements that are unreliable.

Post by **bmcecosse** » Mon Sep 17, 2007 9:56 pm

Usually a good layer of oil protects everything! I guess because of where the master cylinder sits they had to keep all the brake piping nice and low down - and so the T piece where the pipes go left and right just seemed a good place to add the switch.

Post by **bigginger** » Mon Sep 17, 2007 11:06 pm

I've often wondered why they didn't put it next to the bulkhead and run the pipe to the nearside brake across there, rather than in a place so vulnerable to dirt and spray - and damn difficult to get at

I guess maybe the height of the pipe might be the reason though...

Post by **RogerRust** » Tue Sep 18, 2007 7:44 am

I think that before I took it off I'd try giving it a clout preferbly with some suport behind it to try and shock it loose. If not you'll be taking the front panel off soon so do it then. Grab the union with a mole wrench and work the switch back and forwards while the penetrating oil soaks in.

or do what I did and cut the whole darn thing off and do it it the vice. Weld up the damaged hole drill a new one and put it all back!

EDIT I've just noticed that you have fixed it!!

Post by **simmitc** » Tue Sep 18, 2007 6:30 pm

Logically, it´s a disaster, just as the oil pressure warning light is GREEN.

That sounds like a non-standard speedo since Minor ones didn't have green lamps, only red (ignition), blue(high beam) and Orange for oil pressure / filter blocked warning. The mini had a green light for the indicator repeater.

Post by **Willie** » Tue Sep 18, 2007 7:02 pm

I fail to see how the location of the brake switch has anything to do with its life span. The working parts are completely enclosed inside the switch and impervious to road salt etc. The only problem could be with the contacts which are easily cleaned. My '57 switch looks to be the original and is working perfectly to this day.

Post by **bigginger** » Tue Sep 18, 2007 7:13 pm

Lucky you

Still think it doesn't have to be so difficult to get at, though