I used monofiliment fishing line. Much stronger than dental floss....

 

Get two 7mm wrenches. It helps if one of them is a ratching one.

Work from inside the cabin. Self explanatory. 20 minute job. I’ve done it twice.

 

Among the different strokes for different folks, I opt to use a spring clamp on the brake pedal arm and let the grip hold the switch assy in place while I remove the 2 nuts under the bonnet.
For the reinstall, I feel for the firewall boss to locate the 2 holes while holding the assy, and having inserted the 2 threaded studs, I again use the clamp to hold in place to reinstall the nuts.

 

Hi Sarge this is my next repair on my 2006 XK8. I'm not a mechanic but I'll try anything once. This may be obvious to everybody but me but why take off the top plastic piece and then remove that part with the two 8mm nuts? Is it just so you can see from the top where to reattach the brake switch??
Also you would you have the part number for the the brake switch? I can't make it out from the picture.

Thanks for your post!

 

Do not purchase a new OEM brake pedal switch. Replace the two mediocre microswitches on its circuit board with better ones. You will save substantial money and have a much more robust unit as well....

 

Having just done this on my car, these are my observations

Firstly, those of you who can get at the plastic part only to remove it, well done. How did you actually get to it? There's so much insulation around there with no obvious ways to take it out, I ended up cutting a section out allowing me to remove the complete bracket

After literally 4 man hours trying different things, we have the technique down to a T now - I'll explain why later.

Removing the drivers seat is necessary unless you're 5. I'm 6' and 18 stone, my son is bigger. Removal of the sear meant we could actually get into the footwell area, but you still can't see anything

Removal of the switch is easy - two bolts, the electrical connector (have a look at pictures to see how it splits) and a bit of twisting and wiggling it pulls out easily

The quickest way we found to refit - tie a length of fishing line around the stud bolt - nothing thicker will actually allow the bolt and guide through the bulkhead holes. I found a doubled up piece about 6" long was best, with tape to close the "loop" about halfway along to stop it tangling. Do this for both studs. Put the switch and fishing line in the footwell

Working from above, get a length (about 3') of plant support wire, the stuff you use in gardens - the stuff I've got is quite rigid and worked well. Feed one length in to the top mounting hole and attach using masking tape to the fishing line on the top bolt of the bracket. You will need a second person in the footwell to guide it through into a clear area, and pull it down to where it's easy to work on. Repeat with the bottom hole.

Once the support wire is connected to the fishing line, start pulling both through from the engine end - carefully, with the person in the footwell just guiding and supporting the bracket, until it's in the correct area. You should now have the fishing line, instead of the support wire. The person in the footewell then needs to depress the brake pedal using their head - you get more travel and space if the engine is running. Gently pull the fishing line to bring both bolts through the hole - the person in the footwell just needs to support the bracket, you should be able to pull it through from above. ONce both bolts are through, keep the tension on one fishing line whilst putting the nut on the other bolt (bluetak is recommended, along with a long extension bar on the socket). Put on second nut, get the person in the footwell to re-make the electrical connection and release the brake pedal, making sure that the bar on the pedal engages correctly with the switch. Nip up the nuts, and crack a can open before you re-fit the seat

The reason why I had to do this 3 times? After the first re-fit I found the lever of the microswitch in the footwell after we'd fitted the complete switch. I must have loosened it when I took the switch apart to check something (the pictures all show the plastic rotating part flush with the switch, mine wasn't and shouldn't be because it's a newer model / ACC / twin micro switch) and it fell out during the first few hours of fudging about trying to get the thing back in (2 of us trying various methods blindly by feel- rotate it towards next door - no, the other next door!, using string - too thick, single strand fishing line - snapped, long doubled up fishing line - got snagged in the mechanism etc).

Removed the switch and re-fitted quickly using the method above - then I over-tightened the nuts on the bolts and pulled them off the bracket. They don't need mech torque - just a nip

Removed the switch, tacked the bolts back on and hoped for the best - fitted and nipped up, job done

Hope this helps someone else

 

Thanks Jon89!
Where would I purchase the microswitches? Which ones do I buy?

 

The switches I used were RS stock number 6821557, the levers need to be formed and trimmed to sit the original

 

I typically order microswitches from www.mouser.com....

 

I have made this comment on the removal/instillation of the bracket a couple of times previously. I have replaced 3 of these. It is not hard and you don’t even need to lift the hood.

Get both an 8mm standard AND ratcheting wrench. Trust me. You will find that employing different wrenches at different times will be helpful.

I worked on my knees leaning into the car to see/feel under the dash where the switch is. After figuring out this technique it takes me about 15 minutes to remove and replace this switch.

Your height doesn’t matter because you’re only leaning in as far as you need to. And you don’t have to remove the seat, though pushing the seat all the way back is helpful.

The only thing I found once was that the nuts were 7mm and not 8mm. Has anyone else encountered this?

 

Always found they were 8mm,. The top one doesn't need to be removed as the switch is slotted, only the bottom, which is where the ratchet comes in handy!

 

I replaced my switch recently after months of anxiety over the purported difficulty of the task. I did exactly what you suggest. After receiving the new one in the mail, I realized the top locking nut holding the switch to the bracket was slotted and the bottom one easily accessible, I decided to leave the bracket in place and replace just the switch. The seat came out and I hoisted my 6 ft. self onto the floor and began the process. It went like this: 1. Curse and try tape and wire and such to hold the insulation pad out of the way before cutting the flap off with a razor to get access. 2. Gawk at the installation and compare it to the new switch upside down to get oriented. 3. Unplug the old switch. 4. Remove the bottom lock nut from the switch. 5. Fight trying to get to the top nut to loosen it. 6.Climb my 65 year old fat *** out of the car and loosen the mounting bracket nuts substantially but not off. 7. Recline once more. 8. Push the bracket and switch to one side and use a small ratchet to loose the top nut about a half turn. 9. Pull the switch off the bracket (straight down). 10. Depress the adjustable lever in the switch to open the cavity as far as possible. 11. Slide the new switch upper slotted end up under the top nut previously slightly loosened making sure that it is as tight as it can be while allowing the bottom to be guided onto the stud. 12. Tighten the bottom nut. 13. Tighten the top nut by pushing the bracket to one side to get access. (Mine was still a pain so I gave up after getting it down far enough to eliminate most clearance) and tighten the bottom nut.. My logic was that once the bottom nut was tight it had no place to go and would simply bottom out against the side of the slot if it moved at all and stop there). 14. Maneuver the assembly sideways to the position it will reside in being careful to guide the actuator pin on the pedal into the cavity on the switch. 15. Hoist the previously mentioned fat *** out of the car, pant for a few minutes and the tighten the bracket mounting nuts. 16. Recline once again and, using the old switch as a reminder of what it looks like, feel up into the cavity, find the adjustment lever on the switch and pull it out to make contact with the actuator on the pedal with the pedal in the at rest position. 17. Push the pedal down very slightly repeatedly listening for the click of the microswitch each time the pedal is moved slightly downward and when it is released. 18. Plug in the wiring harness, make sure it is clear of chafing etc. 19. Replace the insulation plug previously cut out by taping, gluing, or whatever if you care (I didn't). 20. Put the seat back in and call it a day.

This worked well for me, took about an hour and ten minutes and I did it alone. Just one man's story

 

Well done. Never a fun job. I have done the brake pedal switch replacement twice, both times with the assistance of my wife (it is her car, after all). She is the one who must go upside-down into the driver's footwell once I have removed the seat because I am far too tall and broad-shouldered to fit down in there. As soon as we finished the second replacement job, she said "Never again so do not even bother to ask". It is truly a job for a 7-year-old kid if you can find one....

 

I did this on my 04 XK8 convertible and it worked well. I just loosened the top nut and removed the bottom one and it slipped off and on easily. Removing the seat was a must of course. It was harder to disconnect the harness plug than anything else. I was elated that it cured my problem of course!

 

QUESTION: What was it that caused you to replace the brake switch in the first place?

 

The usual suspects are the messages "Check rear lights" and "Cruise not available" alternating on the dashboard message center....

 

Are there any related codes?

 

None that I am aware of....

 

After reading all of the posts, I chose to remove the plastic components and leave the metal bracket in place. All went very smoothly until I got to installing a small zip tie (like the original) to hold the black cable tightly to the switch bracket. I probably could have simply omitted it, but I'm kind of **** about ensuring that everything is the same as it was to begin with. Working blind, slipping the zip tie through a tiny hole, finding both ends, and wrapping them around the black cable -- all while working in extremely tight spaces -- resulted in some choice swearing and several hours of frustration. I refused to give up, though, and finally succeeded. I no longer have a "CHECK REAR LIGHTS" error message and my adaptive CC works as it should.

 

Yep, this is indeed a miserable job for anyone who is not a Munchkin with the flexibility of a contortionist, even after removing the drivers seat to open up a bit more room in the floorboard. At 6-foot-7 and 260 pounds, I had no chance of success down there. My wife handled that job as I worked the monofilament fishing lines tied to the two brake switch assembly studs while standing over the engine bay. We had to do this twice on her car, once in 2012 (with a new OEM brake switch assembly) and again in 2017 (with two much more robust microswitches soldered into the original brake switch assembly that I fortunately kept after the 2012 repair). No problems since going with the better microswitches. She swears she will never do this job again and I cannot blame her for feeling that way....