For the longest time, I would go into failsafe mode when using cruise control. Based on other posts I figured this is related to the brake light switch, but I did not want to spend $200 for a new one (rip off).

The other day I finally removed the switch which does require a bit of body contortions. The switch itself is a fairly simple mechanism. There is a spring, a miroswitch and a pcb board with about 6-8 wires attached. Not much to mechanically fail and, since my brake lights work, safe to assume the microswitch is good. That leaves a wonky electrical connection.

Although the solder joints all looked good, i resoldered each of them using a generous amount of flux. Took all of 5 minutes. Remove and install of the switch is the bulk of the time.

Sure enough, everything now works as it should. 5 minutes work beyond the R&R saved me $200.

 

Solder points do fail and especially so with a pcb that may experience some sort of flex in the course of normal operation.
None the less, we thank you for alerting us to the solution of the problem should others experience it.

 

Handy to know as I've kept the failed switch from mine as I couldn't find anything wrong with it.

 

Sweet, i have the same issue. Any tips on removing the switch? Thanks

 

It is not technically difficult, no real tricks. Its more that after a certain age, getting at things under the dash is not as easy as it once was!

When you reinstall, just make sure pedal is making contact with switch. You should hear it click. If not, adjust ppsition accordingly.

 

Just completed the same. Switch removal is not a huge deal. I took off the knee panel under the steering wheel (4 t27s) but that was likely unnecessary. One 7mm and 1 8mm to remove the single nut/bolt.

Reinstalling the switch is a bit more of a pain as you need to slot the tab onto a short stud. I laid under the dash to complete this.

Cleaned the switch and reflowed the solder joints. Lets see if that solves my problem

 

Yes, it is not a terribly difficult job...for elastic-man. Even with the seat
all the way back, I feel like I am interviewing for a contortionist job.

 

Just don't get 'cocky' until you have replaced a brake switch in an X100.(same switch, different bracket)
The sedan is tough but the XK is WAAAYYYYYYYYYYYY harder!