I brought this problem up about a month ago. had no cruise control and check rear light. finally slowed down to do it. light is fixed. same message and no cruse. guess it's the switch. thank ALL of you for your input.

 

First do a hard reset. Disconnect neg. batt. cable and touch to positive post for a few seconds. It may not solve the problem, but it's easy and cheap.

 

ok, something to do tomarrow

 

Sure as the world goes 'round . . . .

 

You don't mention ACTUAL Battery Voltage. Given the number of such faults that have ended up being caused by a dead or dying battery, you should start there . . . and I don't mean how old is your battery as even new ones are seldom fully charged.

Measure it . . . coz anything less than 12.6V first thing in morning is known to cause "false flag" faults.

Best wishes,

Ken

 

Sorry guys, your all barking up the wrong tree so to speak.

Its the brake light switch. You have to be an acrobat/contortionist to fit it. Its tucked up bodywork above the brake pedal inside the car. You have to undo two nuts in the engine bay then try and find the holes again when you fit the new switch.

I had the exact same symptoms and warning messages.

Good luck!

Update.

Take a look at what happened with mine. http://www.jaguarforum.com/showthrea...tch#post885898 #1519

 

Further update for you

JagRepair.com - Jaguar Repair Information Resource

and

http://www.jec.org.uk/forums/viewtopic.php?f=63&t=9306

 

No, we're not barking up the wrong tree, we're eliminating other possible sources of trouble that are easy and cost-free to check.
Those of us who prefer to throw parts and labor at a problem without looking at other possibilities are welcome to do so. I quite agree that it's probably the brake switch, but since Uncle Jim doesn't have test equipment that can confirm, we're trying to help in the most economical way.

 

+1+1+1+ with RJ.

These forums are littered with hundreds of similar threads. So much so, that many of us combined to write up "Battery 101" which is in the Sticky "HOW TO . . ."

It even happened to me . . . and I've been around Jaguars on the road, on the track, and in the workshop for 50 years. Case in point . . . perfectly good EPB control module and actuator, both replaced by dealer as faulty pre-purchase on my MY07 S-Type. Replaced at dealer cost near $3,000 plus $1,500 labour, they still take pride of place on my workshop "wall of horrors".

Why? Coz once replaced but still showing fault msg and MIL, I negotiated even lower purchase, took delivery and "dead" parts. Got home . . . checked new parts to find, as expected, each was perfect . . . implanted new, fully charged battery . . . and the car, the EPB, the ABS, Cruise Control . . . all the bits that started "failing" have never missed a beat since. Not my wasted $4,500 for a "fix" that fixed nothing . . . nor the extra $3,500 I negotiated off purchase. For an otherwise truly Concours quality Jaguar, it was the quickest 8 grand avoided anywhere on the planet! By comparison, the new top spec Varta battery seen in "Battery 101" was less than $400. Notice that our OP [uncle jim] has these exact symptoms . . .

Frank could well be right . . . brake switch is a known weakness . . . but again, I have 2 on my wall that are perfectly good (and further 2 swapped into cars as working replacements) . . . all 4 had been swapped out when a dying battery was the real culprit. I share the view of RJ . . . and the overwhelming majority of Techs on here . . . always, ALWAYS . . . start by measuring the standing battery voltage!

IMHO, it's easy . . . it's free . . . it just may save you big time . . . but alas, my 2c just ran out.

Cheers,

Ken

 

A bad battery or poor battery connection can throw up a heck of a lot of spurious faults.

I wrote what I did, and I stand by it, because of the combination of the fault reported.

I had exactly the same fault driving home one day. If I stopped the car. Turned the ignition on and off the fault would disappear. Sometimes even for a day. Then it would return. After doing a lot of research I found it was a very common problem and those who have had it recognized it straight away. Since I changed my brake switch, touch wood, it has never reappeared.

I too do not condone throwing money for parts at these cars, but if someone has a more than likely answer I would thank them, not have a go at them.

I have SDD and a couple of other sets of diagnostic equipment but in the end I listened to the guys on a forum who put me straight.

So if the problem is fixed by working on the battery then great, but please let us know if you permanently solve the problem and what it was. I am always prepared to learn.

 

well, no cheap fix. guess it's the brake light switch. have looked at the postings for them. but haven't found any for 70.00. best I can find is around 145.00. any suggestions on a cheaper one?
as always, thanks to everyone who took the time to read my post because i am sure if you just read it you would help if you could
.and thanks for all of the responses.

 

Advance Auto has them listed under Cruise Control Switch, but they only have them when they have them. You might have to try every few days.

 

thank you.

 

If you know someone who has excellent soldering skills, the two microswitches on the switch's circuit board assembly cost maybe $5 total. Have them replaced and be sure to re-solder all the other solder points on the board as well. I just had an EE friend do this for my wife's 2006 XK8 using the original factory switch we removed back in October 2012 when it failed. We installed the repaired switch a couple of days ago and thus far it is working perfectly with no "check rear lights / cruise not available" messages at all. I'm going to have him make the same repairs to the replacement switch we installed back in October 2012 and just removed so I will have a spare....

 

You should review this post.

https://www.jaguarforums.com/forum/x...warning-63241/

Bad batteries have never triggered that error, only a faulty brake switch. I know as I have had plenty of errors from bad batteries on Jags but never that one. If you are of a mind and can solder or know someone who can as Jon89 says this can be fixed for well under $10.

James

 

Careful. They did not like it when I said it was a faulty brake switch

 

Heh! Too late (reaches for Nomex shorts). I do think though that while there is certainly a degree of merit in the nay-sayers posts there is enough non-anecdotal evidence in multiple forums to support the immediate brake switch diagnosis. That error message is specific and is not prone to battery condition and although other DSC and Cruise messages may well be that is not one of them. My XK8 will still spit out an occasional DSC warning message even with a good battery after a cold night with a cold engine which really sucks amps and drops volts on starting under those conditions. Perversely, my XK Dynamic 'R' under the same conditions will not.

It is worth pointing out that even after warm-up and a run when volts are fine my brake switch would still throw a 'brake light/cruise control' error message (until I replaced the micro-switches).

I look forward to confirmation from the OP that switch or micro-switch replacement has cured the fault.

It is worth mentioning (as I see a lot of posts critical of Jaguars being 'sensitive' about batteries on this and other forums) that a very wise and experienced person once said to me 'once you get it into your head that an XK8 is as much a mobile computer as it is a car so you need to treat it accordingly'. Any vehicle which needs a dozen or more control computers and small local network (CAN - Control Area Network) to operate is going to be totally dependent on adequate volts during starting and operation. This applies not only to Jaguars but to any modern vehicle with a flock of processors so attention to not just battery condition but earthing, charging and charging conditioning are critically important. Currently, I only trust CTEK for this task. This does go double for those vehicles with a boot-mounted battery as they may have longer cables to some of the more critical controllers and suffer more voltage drop during cranking. Ladies and Gentlemen - scrimp on batteries at your peril!

James

 

When I was trying to sort a cruise control problem a few years ago I found the brake switch fairly easy to test.

Disconnect the plug and connect the outer pins to a meter and see if the switch is working when the pedal is depressed, then do the same with the inner pins. I don't recall which pin set is for the cruise control, but it's obvious because the circuit will open when the pedal is pushed.

I also agree that it's probably switch that's at fault, but I would not like to remove and repair without testing.

 

The switch is easy to test. The outer two pins are one circuit, and the inner the other. By connecting a meter to the pins (or maybe it's sockets) there will be continuity on the cruise control circuit until the pedal is pushed.

I do agree it's probably the switch, but I hate to see anyone spending the time and money without knowing if the switch is at fault.

 

Every micro-switch I have removed from a failing brake switch has passed a routine continuity test - a test with a meter is not adequate as the normal failure mode is that the micro-switch becomes intermittent. If you didn't get continuity then that would be a fail of course but if you did it would not indicate that there was not a failing micro-switch present.