While driving today in stop and go traffic I suddenly got the amber warning light with alternating messages "check rear lights" and "cruise control not available". Obviously I must have a bum tail light somewhere but it is interesting that this would also affect the cruise control.

Doug

 

Hi Doug,
I would also check your brake pedal switch as well.

Just a thought.

 

If the brake lights go on properly when the pedal depressed is that all I need to know or is there something else?

Doug

 

Agreed. Those two warning messages together are the classic indication that your brake pedal switch is in the process of failing. Keep in mind that changing the brake pedal switch is much easier when two people do it - the smaller person upside-down in the drivers side floorboard (after removing the drivers seat) pushing the new switch into place, and the other person under the hood guiding the two bolt threads up into their proper place through the two holes....

Search this forum using "brake pedal switch replacement" as your key words and you'll understand why this seemingly-simple job requires a freak circus contortionist....

 

+1 on checking the pedal switch.

The switch is actually two switches internally, one for the cruise and one for the lights, which are both actuated by the same cam mechanism when depressing the pedal. So you can have a bad switch that gives you the message, but still have the lights work just fine.

 

Lots of things can cause the cruise control message. My 'check rear lights' was due to contact problems with the cruise control button.

 

Well all the rear lights seem to be okay so I guess that leaves the brake pedal position switch. The JTIS makes it look like this is an easy replacement and there is no mention about removing the driver's seat. But I guess that makes it easier to get under the dash to get at the switch. Frankly I'll probably just pass by the dealer since my aftermarket mechanical breakdown warranty specifically mentions brake switch as something that is covered.

Doug

 

There is a an easier way to replace the switch. After removing the nuts, wind some fine wire around the studs and push them through. Then wind the wire on the new switch and guide it into place while your helper pushes it up.

 

Yep, that's exactly what my wife and I did except we used monofilament fishing line instead of wire to guide the two studs up through their respective holes. Still not an easy job, though....

 

I tried at least locating where the switch was using a mirror and light rather than squeezing upside down into the foot well and it looks pretty gruesome to get to. The last time I did the lying-on-my-back-under-the-dash thing I ended up pretty dizzy and nauseous. Since I verified that this would be a covered item under my aftermarket warranty I think I will take the opportunity to use a highly recommended local independent and at the same time have them try to play with the window adjustment (gap at the passenger side quarter window where it meets the front window). The last time I visited this shop just to check it out I was impressed with the guy's knowledge and he was well aware of how to deal with the windows.

Also, when I was looking under the hood I noticed some coolant dripping at the coolant filler tank due to crappy fittings on a line that goes to the tank so I will probably have that addressed as well.

Doug

 

I'm getting the "check rear lights" and "cruise control not available" message intermittently. I pulled the switch mechanism and tested both switches with an ohm meter and both work fine (unlike the micro switches used to lower the window slightly in the convertibles in the door latches; they were non-functional).

I've found suitable replacements for about $5 each; can't get myself to spend $160 for the part at the dealer.

So before I go and replace the switches I wanted to ask those that have the same problem what the condition of the switches were when the part was pulled from the car. Did they work correctly, intermittent, or not at all?

Thanks in advance.

Also, just got the windows tinted (dark) and it looks great.

 

As an update--I meant to post that the problem suddenly has suddenly seemed to go away on its own. I was getting set to bring the car in but I have not gotten the warning message again and the couple of times I tried the cruise control it worked fine. Maybe there was some dirt or something in the brake switch and I realize I should probably go ahead and have it replaced anyway.

Doug

 

When it happened to me, it was a dry solder connection between one of the microswitches and the pcb. Pcb is double sided, with only one of the connections on the underside - and that was the faulty one!!

 

DrDSP,
I am wondering which micro-switches are used. Do you have a part number and brand, or a digikey link, or something? I don't want to take the brake switch assembly out without provision (parts) to fix it and put it back together.
I am suspecting my problem is related to the brake switches, as I started getting the "Check Rear Lights" and "Cruise disabled" messages. I checked the bulbs - they are all good. No melted tracks on either side's rear lamp holders. But sometimes when I haven't gotten an error and I press the cruise control switch I immediately get the message "Cruise disabled" as if I had also pressed the brake pedal.
Which makes me think I have the brake switches problem.
Thank you.

 

Would anyone who has replaced their switch be willing to send me their old one, please? I would be glad to pay postage or let me know if we could work out something. I would like to find parts (exact replacement switches, perhaps) and fix them. It would be a real help to others on the forum if we can accomplish this.
Thanks,
John.

 

I found some suitable replacements for the micro switches in the brake/cruise control assembly. Attached is a short doc describing replacement and data sheets for the switch options.

I looked at the original switches when I pulled the module and they looked and tested good. I replaced them anyway and no more brake light/cruise control warnings.

 

Thank you very much. Fantastic write-up. Worked like a charm for me. I got a few extra micro-switches, and I will send to forum members a rebuilt switch for $25 including postage if you will agree to send me back your old one (that way you are not stuck for a few days with your car apart). PM me or Email me at john_sullivan (at) bmc.com if interested.

 

See my latest post on this today
Error code scan details and part details in that post re: faulty brake sensor replacement fixed it perfectly .

 

Newark seems to not have the switches in stock.
Get them from DigiKey.com P/N 480-3630-ND or Honeywell Switch P/N ZD30S60C02-Z .
This has the straight lever which actually saves some hassle over straightening / flattening the simulated roller.

I am raising my refurbished switch price to $35 pre-exchange. I like being helpful, but was investing over an hour of my time for only about $5 after paying for parts and shipping, postage, etc. I had to get a new soldering station, and I don't have enough time on weekends for all the my own projects and honey-dos. Sorry.

 

2003 XK8

I worked on this switch install on Friday afternoon. I purchased the rebuilt switch for $25 from John Sullivan who is on this thread. I have not completed the job yet so I will update to confirm the switch from John is working. While the seat was out, I decided to take care of the "dead pedal" foot rest for left foot. I am building it up but I need some special sized bolts that I won't be able to get until Monday so I won't know until then if the error codes concerning rear lights and cruise control have gone away for good.

The removal of the seat is pretty straight forward. Just remember to get it raised as high as it will go and then move it all the way forward to get the back T40 fasteners off and then the opposite for the fronts. Raise the steering wheel all the way up and all the way in toward the dash to aid in removing the seat from the car and making room to duck under the steering wheel when getting into position to remove the switch. Disconnect the battery.

When the 4 fasteners are off the seat rails, tilt the back of the seat forward, and then tilt both the seat section and back section as a unit (closed clam shell), back toward the back seat...so it's doing a wheelie. I then put some brick supports under the rails to hold the seat in that wheelie position so I could work on disconnecting the wire harness in two places. I don't do much work on cars so I don't deal with these connectors very often and therefore I have to figure out the puzzle each time re: the release points. I'm sure for most of you reading this, these connectors are very straight forward but it always takes me a few minutes to figure out what I should be pushing and what I should be pulling. The wire harness splits off to two different connectors. On the small one, there is a clip that needs to pried open to release the wire harness. On the larger switch, the wire harness is taped to a "T" shaped mount. The tape needs to be cut or unwound. I cut it using a razor putting pressure down in the area where the tape is covering the plastic "T" mount thus minimizing the chance of cutting any wires in the harness.

After disconnecting the seat (fasteners and wire harness), remove bricks so seat is flat, then pull seat towards you, (still in closed clam shell form) like you are rolling it sideways out of the car, tilting it out from the highest point on the seat while it rotates/hinges on the left seat rail. Once you get it over between 45 and 70 degrees, you can safely lift it out while rotating the seat package horizontally, as if the backrest of the seat was going to lay flat against the left rear corner panel of the body. This action gets the metal rails away from the paint to minimize the chance of scratching anything and it feels like the most ergonomic way of handling the seat.

Now get your 1/4" drive socket set out. Use a short handled ratchet, a deep well 8mm socket, make sure it is locked for unfastening, get your lighting in place and then contort you body to a position with your right arm and hand leading the way, on your right shoulder/back. You can't be flat on your back because your shoulders are too wide and you would never be able to get your arms into position to do anything useful. Pull apart the short connectors on the insulation so it is "more" free to move out of your line of sight and work area. You will see the end of the switch and a "relatively" easy to reach 8mm nut that needs to be removed without dropping it or losing it...not so easy. You will also see a white zip tie near that nut that is holding the wire harness from the switch to the bracket that the switch is mounted to. If you are working with John Sullivan, getting a rebuilt and returning to him the switch you take out, you need to be very careful cutting this zip tie. A razor blade won't work. The best tool for doing this is a small wire cutter/pliers or maybe even a larger finger nail cutter. The zip tie is tight around the wire bundle so you need to be precise. I had the right tool for the job so it worked out ok.

The back nut and zip tie came out pretty easy and not much time had ticked off the clock at this point. But, now I had to loosen the nut for the front of the switch just enough to relieve the pressure on it so I could slide it out while leaving the nut on the post. I spent the next hour and half trying to engage that nut with a shallow socket, a deep well socket, the flexible ratchet etc... Not once did I get the tool on to the nut. Even if I had engaged the nut, there was no room to move the handle of the ratchet. I went to the hardware store to buy a ratcheting open end wrench and once again, I was never able to engage the tool on the nut. I was about to give up on removing just the switch and instead remove the bracket holding the switch. If you've read this far, you know that is no fun either. As a last try, I decided to try to lift the rear of the switch off the threaded post and then pull down to see if I could slide the open U-shaped capture on the switch, held tight by the nut, right out from under it. I figured I'd still be "screwed" if this worked because how would I get the new switch back in and even if I did, how would I tighten it down on the front end? Well the dang thing allowed me to torque/bend up the rear and get the switch hole over the mounting post without anything breaking. And then, to even greater surprise, it seemed like it had a lot more play than I expected and maybe it was coming out of the front fastener. Well it wasn't a straight slide out but after lots of wiggling and position changes it came out. Now I could see the front post. It does have a nut (I think) but it also has a "stand off" for the U-shaped clip to slide under. I'm not even sure if one can tighten this down?? It's really hard to see in there and very uncomfortable and my state of mind at that point was focused on finishing this job. I got the rebuild switch into position and on the first try it slide in perfectly....pure luck. I thought this install was going to be at least an hour of trial and error but I got lucky on this part of the job. So it's in, the nut is back on, the connectors are connected and I'll see if all of this was worth it on Monday.

The remainder of this are some pictures in chronological order that might be useful to someone who is "stretching" themselves to try something a little harder than they would normally do. It shows some of the basics and a lot more detail than is usually given via pictures in these reports. I wrote it for someone at my level who is NO Mechanic and unfamiliar with working in such tight spaces. Hope it helps you out and let me know if the new switch goes on as easily for you as it did for me.



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