cudos to all who were successful in replacing the brake light switch and great tips from all above...i tried them all...but...
after 6 hrs, a dislocated shoulder, a pending divorce from my spotter who swears she never saw the studs anywhere near the holes, i called it quits
i enjoy most repairs but this was pure torture that could only have been designed by an engineer who never had to actually do it
i gave the prepurchased switch and $100 to my mechanic who installed it but asked me to never come back with another one
dan314

 

you say you tried everything--but did you pull the driver's seat?
I wasted an hour, and was almost as frustrated as you sound--but did it relatively quickly after pulling the seat out, which is well worth the time it takes in the long run--pulling the seat takes maybe 20 minutes, and is easy.

 

So to all the people that have replaced their brake switches: DID IT FIX THE PROBLEM?

Last fall when I was sorting out the bugs on my new to me '97, I got the "Engine Fault" message when trying to use the cruise. No problem, this thread says replace the brake switch. Did that last fall and never got around to driving the car.

Flash forward to last week when I finally started driving it daily. Set the cruise on the drive home and got the "Engine Fault" code with no lights or CELs. Shut off and restart and no message.

Can that switch be bad already? Can you test them with a multimeter to tell if they are within the specs? I (my bro)just got the JTIS downloaded yesterday and have not had time to search.

B

 

When I was having trouble with this switch, I took it out, checked it with a meter and convinced myself that both microswitches were good and could not be the cause of the 'No Cruise Control-Check Rear Lights' message. Before re installing (With all the frustrations already detailed!!) I removed the tie wrap holding the wire to the bracket so in future the switch could be removed from the bracket by loosening the upper nut over the slot and removing the lower one. Just as well, because the fault was still there and out it had to come again. This time either I was more careful or maybe lucky, because it became apparent that there was a bad soldered joint on one switch terminal that was intermittent. Though not obvious to a quick look, the small printed circuit board on which the switches are mounted is dual layer. Only one switch terminal is soldered to the upper layer and that was the problem - its not easy to get at. I solved it by de soldering the joints to remove the offending switch and then re soldering - easy as that! With the switch fitted back to its in situ bracket - much easier than switch AND bracket - the problem had absolutely gone. I'll bet that a significant number of these brake switch faults are the same, because if you think about it, microswitches are just not that unreliable in themselves, so check your soldered joints before buying in a new switch assembly - possibly with the same defect!

 

Dan, I have to agree with you. This was probably the most difficult repair I ever did on this car. I even pulled the seat so I could contort into the proper position to reach everything. In the end I realized that you can only get the switch back into position by depressing the brake pedal WITH THE ENGINE RUNNING. The pedal doesn't move far enough with the engine off. Once I started the engine and depressed the brake pedal (with my hand while laying on my back), the switch bracket slipped into place and my gorgeous spotter (from whom a divorce is not pending and she was buck naked at the time) was able to start the nuts onto the three studs.







OK... I exaggerate a little. She wasn't buck naked.

 

thanks.. i found the video for seat removal and it looked easy but by that time i threw in the towel

 

yep, it fixes whatever false error mssgs are triggered by the bad brake light switch. apparently the specific false error messages differ between models.... in the case of the XKR, the bad brake light switch also triggered "cruise control unavailable" and "trunk (bonnet) open" ... mine went out at only 37K mi.
dan314

 

easier to just pull the switch apart using the 'Gus Approach' then removing from the firewall entirely...especially if you don't have a significant other to watch for studs.

Yes, I did it, and it fixed my intermittent cruise control failure. If the CEL is on, there is a code. Before shutting off the car, get thei code pulled, otherwise on startup, it may be 'self-cleared'. Check your cruse if it happens again, only way to be sure.

 

I think you guys that get the switch installed in 10 minutes must be Gods or really small contorsionists. To do mine I removed the seat, door sill, kick panel, and pulled back the insullation so I could get my hand up there. Pieice of cake thanks to my wife guiding me. Took about an hour.

 

Kudos to you!

 

If you look at this pix notice the switch is all the way to the stop.
when installing the switch be sure not to push to hard on the switch or it will go out of adjustment and not return to the right position and won't work right. The brake lights may work but the cruise control won't and limp mode may come on.My old switch was in this position when I removed it and when I pulled it to the right position it worked fine.

 

You guys must like to work harder than necessary. I don't change the bracket, just the switch. Two 8mm nuts, loosen one, r&r the other. 15 minutes. No seat removal, but I'm skinny.

 

that's the gus manuever i speak of

 

I would say, don't try this at home--but your post makes this doable. Definitely a two-person job. Thanks!

 

I've just checked my switch with a meter and found that the Brake Cancel switch (NC) is always open so I guess I'm about to try the removal.

Given the discomfort involved just in testing the switch I'm opting for the "Gus maneuver". Will I need to follow Reverend Sam and press the brake pedal with my head in order to reinstall the switch? or is that step reserved for the hard core team that remove the entire bracket?

Also - in reading JTIS my guess is that the approved Jaguar way would be to remove the entire brake pedal assembly. At $90 per hour it's a good game while it lasts I guess.

Kudos to the contortionists that have succeeded - even with visual encouragement from their better halves :-)

Thanks for all the pointers here ...

 

you won't need to mess with the brake pedal if you don't remove the bracket w/ the switch. Removal of the seat, however, still aids the upside-down procedure.

 

Firstly a HUGE thanks to you all for the pointers. I completed the job with rather less pain than I expected. I couldn't find a way to undo the top nut on the bracket for the Gus maneuver so ended up removing the entire bracket instead al la Reverend Sam. When I tested the switches they were fine so I resoldered every joint as a precaution and put it all back (in under 5 minutes). Cruise control magically works again - happiness.

In case anyone else needs to do this here is what I found to work ...

DON'T USE YOUR EYES - they confuse everything! I actually shut mine to eliminate the distraction.

Before removing the bracket feel around the top of it and you will find that the plate fits into a neat space with no spare room - this is a useful hint.

When replacing the bracket feel for the bolt holes before attempting to install the switch - specifically feel for the rear bolt hole (closer to your feet since you are now upside down on your back with you head on the brake pedal - thanks Reverend Sam). This will orient your world and save *lots* of time groping in the dark.

Next slide the switch onto the actuator bar (requires the RS move of pushing the brake pedal with the bonce although I didn't need to start the engine). Don't worry about the bolt holes yet - just make sure that the open side of the slot is facing "up" - i.e. towards the top of your head.

Placing your index finger on the end of the rear ("bottom") bolt gently slide your nail around until you feel the bolt hole again. Now ease the bracket past the end of your finger and, hey presto, in it goes. Once the first bolt is in place the second one naturally follows with a minor twist or two. Luckily the whole things gets held in place by the actuator bar so you don't need a sky hook to stop it from falling out.

I hope this helps those unfortunate enough to have to try this for themselves.

BTW. I never managed to get the front seat out since I can't find a T35 Torx bit and T30 is too small and T40 too big. I saw mention somewhere of a Torx Plus TP27 but that is a problem for tomorrow ...

 

I just re-read this entry and think it could be very significant. When I removed the unit the adjustable portion of the switch was not all the way out to the stop. I inadvertently pushed it all the way in and had to pull it back out again. Since the movable part appears to ratchet against the main cam I suspect this is actually a self adjusting device. It will be interesting to see if the problem reoccurs next time I have to haul on the anchors in earnest. I'll keep you all posted.

 

My hands are the size of catchers mitts so there is no way I can stuff them into that small space far enough to feel for the two bolt holes. I still say that anyone who can do this job all by themselves is a freakin' magician along with being a circus-quality contortionist....

 

I just completed this job on my XK8 after putting it off for a long time, due to some of the horror stories I read on here.
I did find a very easy way to do it not mentioned in any of the above posts and had the whole job done in about 30mins (including seat removal and refitting). I was not sure if my method would work, so I never took any pictures of the procedure, so I will try to explain what I did.

First the drivers seat was removed and the old switch also removed (instructions found on this site).
I then took the new switch bracket and drilled two 2mm holes near where the bolts meet the bracket (the red dots in the picture). 1 hole near each bolt.

I then took an old extension cable and removed 1 strand of wire, removed the sheath and split the cable down the middle to make two thinner wires.
I fished one down through the top hole of where the switch is bolted to the body and then tied the end that came into the cabin through the top hole I drilled into the bracket. I repeated this for the second cable and tied that one through the bottom hole on the bracket.

I then got a quick release clamp to push the brake pedal back, plugged the connector on to the new switch and placed it roughly in position.
Then I moved to the front of the car and gently pulled the two wires up until the bolts came in contact with the bulkhead, a bit of wiggling and the two bolts came through. I then put on both nuts and snipped off what was left of the wires I used to pull it into place.

I then removed the clamp, and tested the new switch which worked perfectly!

Many thanks to all who have contributed to this thread, I donīt think I could have done it without all the info!

Next job for the car now is to identify an oil leak and get it sorted, no doubt I will be back asking you guys what need to be changed and how to do it!

John.