Several months ago, I started getting intermittent Cruise Not Available/Check Rear Lights messages. The cruise didn't work at those times, but I would have brake lights. Couple of weeks ago, though, a guy pulled alongside me and said my brake lights were always on. Obviously, it was time to tackle the dreaded brake switch replacement job. (You can check Gus's instructions here: http://www.jagrepair.com/XK8BrakeSwitchReplacement.htm)

First step was to remove the seat. It takes five minutes and is absolutely necessary. The quarters are close enough without having to contort your back further.

Bob Gauff (Motorcarman) told me his preference was to remove the switch along with its bracket, and suggested I might poke shrink tubing down one of the mounting holes and affix it to one of the bracket's stubs so I could pull it up and into the holes. I tried that but the tubing pulled off. (This should have worked. I think, in retrospect, that it was snagging on the frame and I may even had the switch turned backwards.) I tried light monofilament, but it kept coming off. Then, I decided to try Gus's stick method, but the switch kept wiggling around on the stick I had. Trying to get the switch positioned by hand was near impossible. I couldn't see anything once my hand went up to position the switch. All I managed to do was scrape up my hand and not come near the holes.

At this point, my daughter – who even though she is twenty years old, is very petite – offered to try. I was skeptical that she'd understand what I was trying to do, but I was glad to let her try. Thirty seconds later, she had the bracket in position and I was able to screw on the nuts. Unbelievable! (Her hands are about half the size of mine.)

I was going to take pictures, but I could not get any sharp and bright enough to show anything. It really doesn't matter. Lying on your back with your head against the floorboard, and your hand(s) under the dash, you really can't see anything. The only useable shot is below and it shows why my switch was not working. Both contact springs on the microswitches were broken off. I guess one went, followed couple of months later by the other one.

If I were doing the job again, I think I might try just removing the switch from the bracket, leaving the bracket attached (an approach Gus also felt worth trying). Even though you'd be flying blind, I think your fingers could probably see the nuts that hold the switch to the bracket pretty easily and it takes very little pressure with a small wrench or socket (8mm?) to loosen them, removing only the bottom one and sliding the switch down a tad from under the top nut. It would only take a couple of minutes to try that method, and if it works, Voila!

I'd still take the seat out. You'll even find some spare change and maybe someone's lost earring. Whatever, it will give you an opportunity to really vacuum out the junk that collects under and around the seat.





Board from old switch on right.

 

One note to mention is that those switches on the board are the same ones inside the boot lid latch switch.

I had to unsolder a switch from a faulty brake switch assy and install it to get the car out of VALET MODE when the customer's knee hits the button.

The latch has a switch assy that comes apart and THAT micro switch is inside.
I think I had to swap metal levers but it worked!!!!

bob gauff

 

McGuyver would be proud of you! Thanks for your help.

 

Congrats to you and your daughter. Until an owner attempts this job, they really have no understanding of how challenging it is. The smaller the person on their back in the floorboard is, the better the chances are that he/she will be able to get the new bracket in place in a reasonable period of time. I had my wife do it while I leaned over the engine bay and pulled the two monofiliment fishing lines I had tied to the bracket studs up into position and quickly got the first nut on once I had the studs poking through....

 

Thanks, Jon. I wanted to add one more detail to this job. Prior to my replacing the switch, the transmission would usually stay in first when moving from a stop, unless I used the j-gate to shift, starting off in 2nd. That fault, which never triggered any transmission code, disappeared with the new switch.

Great relief to know the tranny's okay. It was explained to me that the broken brake light switch told the computer, which told the transmission, that my foot was ON the brake all the time, so the tranny would want to stay in 1st, since it thought I was stopped.

I swear, every time I fix something on this car, I love it more. I'm talking nice, easy jobs I can do myself. No crankshaft replacements or such. ;-)