Rear Brake Switch on 85 BMW K100RS... DEAD?

[VashonKbike]

I'm troubleshooting my brake light which is not working.  Doesn't come on at all.  The bulb is good and there's no current going to it.

I thought it might be a rusty connection but cleaned things up a bit with some Deoxit and still no go.

I was looking into the Rear Brake sensor and found what I'm guessing is a bad switch/sensor?  Check out the attached picture.  I'm assuming this should be the same as the front brake sensor where the little pin at the end sticks out a bit so it can go in and out. - I did check the wiring going to the Rear brake sensor and there is a current there.

I'm a newbie to electronics and wiring.  Any help appreciated. 

1985 BMW K100RS

[rbm]

The plunger in the center of that switch should be sticking out and operate freely.  This one is fully retracted, meaning the switch mechanism is jammed.  You'll need to clean it using electronic cleaner like DeoxiT.  Alternatively, you can steal the switch on the end of the throttle body rail that is used to illuminate the choke light on the instrument cluster.  It is exactly the same switch.

[K1300S]

Looks dead.  The pin switch should move in and out.

New ones are available.  I just bought one from maxbmw.

[VashonKbike]

The plunger in the center of that switch should be sticking out and operate freely.  This one is fully retracted, meaning the switch mechanism is jammed.  You'll need to clean it using electronic cleaner like DeoxiT.  Alternatively, you can steal the switch on the end of the throttle body rail that is used to illuminate the choke light on the instrument cluster.  It is exactly the same switch.

I'm going to try and steal the choke illumination one and see if that does the trick, thanks!

[The Mighty Gryphon]

Yes, that switch doesn't look too good and isn't worth trying to clean or otherwise repair.  It will only fail again, probably at the worst possible time, and you'll have to change it again.

You can easily check the wiring by connecting a piece of wire between the two contacts in the socket the switch's plug goes into.  If the wiring is good the brake light will come on.

[VashonKbike]

I yanked the Clutch switch and swapped it out for the rear brake switch and voila, it worked! 

I was having trouble with the front brake illuminating the rear as well so pulled that one and plugged it into the rear and it's a no go, so looks like I need to find two switch/Sensors -whatever the right term is, for the front brake and the clutch, although the later isn't too important.

Thanks for everyone's help.