My car is a 2003 XKR with 20 K miles on it. I get the warning "Check rear lights" & Cruise not available" after driving the car for 10 to 15 miles. After it warms up, it occurs more frequently. I have read the posts and have tried most things. I removed the rear light holders and tested all bulbs measuring resistance. I have bent the contacts and the bulbs are now much tighter in the sockets. I bench tested all bulbs in the holder and tapped on them when testing. All lights are working. I read on the internet that the message "Cruise not available" is just that cruise is disabled when there is a safety issue somewhere else. I have not looked at the cruise due to this information. I have not disassembled the center light on the trunk as a post on the internet says that the warning system does not include this light. However all bulbs are on. Since the car is with only 20K miles on it, all bulbs are original. the car is stored inside in California so is as new. I have made a list of all times that I get the warning and it does not seem to occur after any one or two events like: braking, turn indicator use, driving quickly, driving slow, all lights on, etc. A long drive (20 miles), not using the brakes, turn indicators, & headlights failed to set the warning this morning but when I went back to normal driving, the warning came back on. I am ready for new ideas. Thanks, Ernie

 

Hi Ernie-
The battery sits on a shelf on the right side of the trunk. On the 'riser' to that shelf are a couple of ground studs with black wires. Check those out and make sure they are clean and tight.

 

I had the same rear light problem with my 97 XK8. Here is what I did to solve the problem. I can't remember who posted this fix.

 

This is a bad brake light switch. Search the forum for your error, or on how to replace the brake light switch, there are several posts about this. It is farly common.

 

I agree with Steve. 99.9% chance that it's your brake light switch. Instructions on how to replace it are in the FAQ thread. A new switch module is about $70. It's a DIY job, but it takes two people to reinstall it.

 

The problem is your brake light switch, which is located behind the brake pedal. A new one is about $70. You can do it yourself, but it's rather difficult, simply because you have to lay on your back on the floor of the car to reinstall it.

The switch module itself has two sets of contacts, one is normally open and the other is normally closed. If one set of contacts goes bad, the ECU will see two switches in the same state at the same time. They are always supposed to be in the opposite state, so when it see them in the same state at the same time it puts the error on the dash.

 

I will replace the brake switch this week. I really appreciate the help as this one had me stumped. The reason that they also give the warning, "cruise not available", is because the brake switch disables the cruise control. This really makes sense to me with this new information.

 

My XK8 started giving me these same messages today. But with a twist. I get the message Cruise Unavailable and sure enough it is unavailable. But if I press the Speed Limiter Switch (a pointless function if there ever was one), which is tied to the cruise control controls, the message switches to Check Your Rear Lights. I did and they are all working as they should, including the brake lights and fog lights. Could a bad brake light switch affect the cruise control and not the brake lights themselves?

 

I still believe this to be the same brake switch problem. Typically, the message alternates between the 2.

 

If it is the brake switch I may just live without the cruise control until the warm weather returns. I rarely use cruise anyway. I always dread any job where I am upside-down under a dashboard. Taking out the seat will help some, but I'm already feeling claustrophobic.

 

I replaced my brake switch and it is a 2 person job. What I did find is if you use the switch striker to line up the switch it is a bit easier to install. This is a link to my procedure if you elect to do the job XK8 Brake Switch Replacement Good Luck!

 

Thanks for taking the time to document your procedure, Gus. I'm sure it will be very helpful if I have to tackle the job.

 

Thanks everyone for the postings! Must be brake light switch season! My symptoms are a little different in that I get the "Engine Failsafe Mode" and "Check Rear Lights" warning. My cruse control button light is out (assuming it is disengaged but didn't try it). I'm thinking this is just another example of the same problem, and from Gus's write-up, I feel pretty safe with that assumption.

I did notice in the write-up that he got an ABS Warning too. I'm wondering...I've had an intermittent ABS and Traction Control not available warning that comes on about every other time I drive the car. The local Jaguar dealership diagnosed this as an ABS Unit (~$4000). I looked around this forum and found posting about bad solder joints in the ABS Module. I've not felt like tearing into that yet although I was just about ready to. My question here is, could it have been a bad brake switch all this time? I know that the multiplexing of signals done in our cars makes it really hard to troubleshoot, and I may only find out by replacing the brake switch, but it would be nice to know if anyone has seen this before.

I also have a question about the switch replacement that Gus documented. At the bottom on the doc it states that one could probably just remove the switch housing from the bracket, leaving the bracket in place. Has anyone tried that yet. Seems like a lot easier fix then pulling the whole thing and trying to line it up again.

My 2002 XK8 has 88k so I guess I shouldn't be sad that I have to replace the switch. I'm sure it has been cycled about a trillion times in 10 years of urban driving!

Thanks

 

It think Matt did the switch change like I suggested and it went well for him. As for the other faults they were related to a TB problem. JagRepair.com - Jaguar Repair Information Resource I have a Procedure for checking the ABS system on my page and it might help in you troubleshooting. It is for a 99xk8 and I am not sure the readings are the same but it should help. JagRepair.com - Jaguar Repair Information Resource

 

Gus, Thanks for the great resources. I'm going to go ahead and change out the brake switch. Also, I've been looking for your ABS troubleshooting and repair guide for awhile! Thanks for sending me a link! Very good stuff! Finally, I've noticed that if my car sits for a week, it is very hard to start and runs rough for a bit. I have to keep joking the peddle to keep it running. I also notice that if I drive someplace and let it sit for an hour, then start it back up, it sometimes idles rough but then smooths out. I know the prior owner had the TB replaced under warrantee, but its sounding like I may need to look into it again. I don't get any ODBII codes, but it appears that isn't always an indicator either.

Thanks again!

 

I would look at cleaning the TB and also replace the plugs if they have not been replaced.

 

I'll give the cleaning a try. I like the idea on your website of drilling the little hole in the intake tube and plugging it with a screw! Nice, elegant solution!

The spark plugs were just replaced by me about 5k miles ago, so I wouldn't think they are the problem.

Again, thanks for all the advice!

 

Log the engine codes too...free at the auto parts store. The brake switch is not responsible for the failsafe message. If the brake switch doesn't help the lights message, could just need a new ground on your tail lamps...common fault, but usually on earlier model years. For the rough start, in addition to Gus's cleaning advice, also look for air/vacuum leaks, possible misfire and/or plug fouling.

 

I agree with Matt’s advice and that it to read the codes. I failed to ask the right questions to better understand your situation.

 

All,

Thanks for all the help. The brake light switch fixed the problem with the Engine Failsafe Mode and Check Back Lights problem. It took me about two hours to get the switch in because, for the life of me I could not find the holes in the firewall! It didn't help that I'm 6'3" and the space in the foot well is pretty tight for someone my size. Once I found the holes however, it was a snap!

As for the ABS/TRACK lights and console indicator, they are still on intermittently. I checked the ohm readings on each sensor and each a little over 1k ohm. I know the 1999 trouble shooting says 2K ohms, but maybe something changed between 1999 and 2002? All are consistent within about 40 ohms (none lower then 1K ohm), so I'm going to assume they are good and the electronic module is bad, unless all four senors are bad! If anyone has any advice, I'd love to hear it.

Finally, the hard start problem hasn't occurred yet. The only code I get using my Android phone with Torque and a bluetooth OBDII module is P1111 which Gus said was a common code and not to worry about it. I'll keep my eye on it though and next week I'll give the TB cleaning a try. Couldn't hurt!

Thanks again everyone!

Cheers,