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Hi Fetti,
I went to see my local NAPA store today and he said go to a Napa store and they can order it direct from the factory. Mack (local manager) said that was what he had to do with mine. I did not realize this as I ordered the switch and was then out of town for a week or so, and when I returned it was waiting for me. if you don't get any help from the Napa local send me a PM and i'll get you with my Napa store.
Hope this helps
Rich
I did call my local NAPA and they repeated the same issue as he online store. I went ahead and ordered from Jagbits. Paid a little more but at least I know it's on the way. Thanks Rich!
Guys, You don't need to undo the two screws under the bonnet. Slacken the screw a the top of the switch a turn, then undo the lower one with a mini socket, the cut the cable tie holding the harness, unplug the connector, and simply remove. Replacing is a 10 minute job. I removed mine resoldered the connections and replaced job done!
The connections on the micro switches get tired and although tests out okay on the meter, the connections to the circuit board are dodgy.
If either of the two switches fails, then a fault it thrown. Each switch is thrown when the pedal is idle, and released then the brake is pressed. The right one is a Normally open one for the brake switch and the left one is a Normally Closed for the cruise control. When you press the brake the Cruise is disconnected, but if it isn't then the brake switch will throw an error, check rear lights, cruise disabled. If the brake switch fails, then you can't get it out of park, and brake lights fail. Either way you will throw a fault. So I would get a scanner, clear the codes, start up and press the pedal 6 times, then check the codes again.
I don't know for sure, but on some Jaguar models, 0.2 hours (12 minutes) to replace the switch on the bracket (as opposed to removing the bracket with the switch) might be doable. I doubt it on the XK8, as one really needs to remove the seat in order to get under the dash where the switch mounts on the bracket, and the time to do so would put you over.
I found it fairly easy to remove the switch from the bracket rather than to remove the bracket with switch attached but others disagree.
Well, I agree it was very easy and about 10 minutes to remove it with the seat all the way back, and the same to replace it. Definitely a bit of contortion for my 65 year old body though. I am sure this is where smaller framed folks like me have a much easier time. I could not find anything wrong with the switch (one normally open one normally closed), re-installed it and now works (the BL were on all the time and no cruise). Can't really understand how it got "out of adjustment".
My 1998 XK8 was going into Amber engine fail mode when trying to engage the cruise control, just as others have said. So after reading multiple posts about the limit switch problem, I jumped to the conclusion that this was the culprit. Got a rebuilt part from JS and proceeded to install the new assembly. To my surprise this did not fix the problem. Peeking around under the hood looking for things that resemble vacuum hoses, I came across the "T" connection in the photo with one connection broken off. (see photo) A couple of dabs of RTV on the joint and the cruise is working as it used to.
Checking the mechanical connections first may save you a few hours of time and some wasted $$!
Hi,
I've successfully cleaned my switch and now it seems to work fine.
But it was a real pain (as Reverend Sam said) so I would like to add some tips that helped me:
1. before dismounting all, verify that nuts inside the bonnet are tight. One of mine was a bit loose. Sometimes erratic messages could come from a simple thing like this.
2. Try to dismount only the switch leaving the bracket in place. It's not easy but easier than mount the bracket. Believe me.
3. If you have to mount the bracket don't try to do it alone. It's a job for two (better if both experienced).
4. put a mirror on the footrest and use a led torch to illuminate the area facing it directly to the mirror. Works better than illuminate directly the area under the dash and you can see it from a normal position (helps to avoid to become sick after a few minutes with your head under the dash)
5. Paint the top of the bolts with red paint or similar. This will help your friend/girlfriend/wife to see when bolts are in the correct position.
6. Use two thin ropes tied to the bolts to bring the switch near the holes. This will help your mate to orientate the bolts more easily.
Well I gave it a go and it took me about 2 1/2 hours. I left the seat in and got the switch off with out taking out the mount. That went pretty good. How ever when trying to get the switch on the old mount I just couldn't get it. So I dropped the old mount out. Got 40lb test fishing line and treaded it through a wd40 red spray tube and dropped them in to the holes up top and tied them to the new mount and with the help of our handy man got it in. Started her up and still had restricted Performance, so it took her for a cruise and turned on the Cruise control then braked and the message went off. Success.
Thought I’d add my learnings to the mix on this thread.
First… Seat out is the best way to go on this repair. It’s only 4 bolts (T30’s I think) and two plugs for the electrics, but disconnect the battery before removing the plugs under the seat to protect the airbag circuit.
The best position I found was lying on my left shoulder blade, with my head under the dashboard… Steering wheel fully out and up, feet on the back seats. That let me work the ignition and brake pedal with my right arm and position the switch with my left. I’m in a RHD car though.
Removing the switch and reinstalling it is best done with the brake pedal fully depressed so the perpendicular bar is out of the way. However, initially offering up the switch might be easier with the pedal up, to get a rough idea of where the switch sits, then down again to have room to jiggle it around. I used my right hand to start the engine so as to depress the brake pedal easily, and then used a pre cut piece of wood to sit over the crook of my left arm and chock the pedal down against the front of the handbrake. I could still move the switch around with my left arm that way.
Next… ticking noises. With the ignition on, there are 3 that you should hear as you work the brake pedal, two quiet ticks from the switch unit as the two switches open/close and a louder one from the centre console for the park solenoid. If you don’t hear all three, you have a problem somewhere, and you’ll know where. The two switch pack switches go pretty much at the same time so move the brake pedal slowly to differentiate them.
Next.. switch operation. Not to plagiarise other previous posts, but look at them for images… (I forgot, sorry!) the way the switch works is that in normal use the perpendicular bar on the brake pedal almost completely closes the white cam unit that presses against the two switch contacts inside the switch unit. In other words… if you rotate the white cam manually with your finger, it goes a fair way in before it closes the switch contacts, and importantly, the brake pedal moves up very little after the switch contacts are closed before it hits it’s bump stop. The idea is that a very small depression of the brake pedal (5-10mm) will open the switch contacts and the ECU then knows that the brake is on. The tolerances between two switches being on, one on & one off, and neither on, are very fine though, and I suspect that normal wear and tear of the unit simply causes first one, then both switches to not close when the brake pedal hits it upward bump stop.
In my case, I had a dash warning light saying ‘check brake lights’ and no cruise control… Others have had brake lights stuck on.
The switches ‘seemed’ to click OK when I removed and cleaned the switch unit and contacts. When I put the switch pack back in, The brake lights were stuck on.
When I put my head under the console, I noticed that the brake pedal wasn’t coming up high enough to close the switch contacts (no clicks at all), but lifting the pedal from behind the footpad with a finger by a few mm to the very limit of its travel closed the switches and the brake lights went out and the centre console solenoid tripped.
My solution was to remove the switch again (aaaargh) and superglue a small washer over the base of the threaded post on the switch that was nearest the windscreen. When refitted, this had the effect of rotating the whole switch forward slightly so that the brake pedal closed the switches before it reached the end of it’s travel. Three clicks.. problem solved, and she’s run well for the last 4 weeks.
I suspect that the switch contacts wore sufficiently over time that only one was closing when the brake pedal came up, hence the codes. My messing around with it must have tripped it over the edge into both switches not closing.
Anyway.. that’s £120 I’ve saved that can go towards a throttle body refirb… 😊
OK, I just went thru this aggravation too. Getting it out (using the Sam method) was traumatic. Got it back in almost by accident but fairly quickly. Here's what I did / learned:
1) Son is a EE, and helped me with the switches on the PCB board. The switches were ok, but testing the circuit, it was not a good connection - erratic. He melted and resoldered the connections, and then there was a good connection. Just used the audio on an ohmmeter to test. Put it back in and it works. Which is great since the switches I ordered hadn't arrived yet... TBA how long it lasts, but son thinks it's a good fix. So it might be worth trying this (as a few others in this thread did) rather than a new part or new microswitches.
2) The part discussed in this thread, with the Cherry switches, pn LJB6420BA, with pics above and widely referenced with the PCB board -- is DIFFERENT than the older style pn LHF6420DA. Pic of the older one below for comparison. My 1997 that I parted out had the older LHF switch, and the micro switches are NOT attached to any PCB. The older one also has slightly different microswitches which say Burgess on the side. So maybe only the newer versions are the ones that are failing - have not seen that referenced, but IPC says the newer ones are in VIN 18108 and up. I think from looking online that these should all be interchangeable.
I didn't realize this until now, after wondering where was the brake switch off my part out and digging it up. I left it attached to the booster by mistake, didn't realize I had it or I would have just used it. In other news, I have the old style brake switch for sale LOL.
The resoldered connections lasted about 3 weeks, and then the cruise fail / check brake lights msg came back. Pulled it and sent to son with some new microswitches to solder.
In the meanwhile, put in the old version switch as described in #2 above. First drive, got restricted performance immediately, with no msg. Crap. Investigation revealed the cross bar on the brake pedal that deflects the switch when the brake pedal is NOT pushed, was not deflecting the brake switch sufficiently. So the brake lights were always on - the car thought the brake pedal was always pushed.
I tried tightening the bolts on the brake switch, thinking maybe it wasn't setting properly. Managed to break one bolt. Grrr. However, it was still pretty stable with only one bolt.
Solution - made a bushing with duct tape, and slid it over the brake pedal cross bar. Increased the cross bar diameter from about 1/4" to about 3/8". That did it. Just enough extra to cause the microswitch to engage when the brake pedal was released. All better. I doubt this is a permanent fix, and will go back to the original switch when son gets it done and back to me.
Double check the "trigger" part of the brake switch. There is a ratchet mechanism that needs to be extended after a repair. You can see it plainly in the picture right above. That is the area with the teeth. These parts can slide/ratchet. This is for your brake lights, etc.. and your safety in traffic. You should not need any home-made one-off remedies for this...
I agree completely with fmertz. Your picture shows that the ratchet mechanism is completely collapsed/compressed, which is why your bushing trick worked. Undo it, release the ratchet and be sure the brake pedal is part way down when you re-install the switch. When you then release the pedal, it will compress the ratchet the proper amount.
People (myself included when I first went through this) seem to want to test the switches, decide they are OK, and put them back in, only to discover they still have the problem after a few days or weeks. These switches have a life expectancy of a certain number of operations. I calculated that in typical use, that would work out to about 50,000 miles, give or take. You will have no peace until the switches, or the whole mechanism, is replaced with new.
Fmertz & jsulliva-
Took your advice to heart and did remove the switch and re-adjust the rachet mechanism. Removed my duct-tape bushing and it all works as designed.
Had to take the switch out again and re-install but I am starting to get good at it.
For those who have left the bracket attached, were you able to swing the switch fore (or aft) so the spring-loaded switch did not interfere with the activating arm? And if so, after the top was inserted did you just swing the switch into position so now the switch was engaged?
You can use a helper and depress the brake pedal for some clearance. If the engine is running, vacuum will be applied to the booster and give you even more space as the pedal plunges a bit deeper.
I know I might get some flack for this, but on mine, the best way to replace was to take it to the dealer. I bought the replacement switch on-line to save money, and during a service where they replaced the front oil cooler and hoses, had them install the switch. $80 in labor was worth me not having the frustrations and hours spent by others I have read about in this thread.
On the X100, mine's the 2003 4.2, you undo the top nut a few turns, snip the cable tie, and remove the lower nut, and just take it out. Putting back is just slip it under the nut at the top and locate it over the lower stud and slip the nut on. The top of the switch board is a U shape so it can slip under the nut without it being fully removed, if you see what I mean. It helps if you are slim to tuck yourself under the dash. Mike
08-18-2015, 08:00 PM
