I have a 05 xk8 with 26k on the clock. I have owned it for 1 year and untill the last month have had no issues. However, in recent weeks whilst cranking the car the 'dsc system fault' has appeard in the display, but only lights for a few seconds then goes. The car has failed to start twice with 'Cruise not available' and 'restricted performance' both appearing in the display. However with a few minutes the car will start and no warnings are visable. My local Jag dealer has had the car now for over two weeks and says cannot get it to fault and nor are any codes being logged. alot of scratching of heads, but no joy in fixing it .. any ideas please ??

 

Do you drive the car pretty frequently or are there days that go by when it is garaged? I am asking because for the first year after I bought my 2005 XKR (back in August 2008) the Jaguar was the 3rd car in a 2-driver family and it sometimes was only used once or twice a week. During that period I would occasionally get warning lights that would disappear the next time I started the car. Since the car has become a daily driver (beginning of this year), those types of phantom/false warnings have pretty much gone away. Similarly, I believe there are a lot of things in this car that end up working better when the car is used frequently versus being a "garage queen".

Doug

 

I think you might have two problems. As for the Restricted Performance check and clean your air filter, MAFS, TB and breather stub. At the same time check your air intake hose for cracks. As best I can recall we have had 2 situations where a knock sensor actuated the restricted performance, my car and one other on this forum and both times were without codes.

https://www.jaguarforums.com/forum/s...ed+performance

 

I have to wonder the same thing. My 97 was fine all winter, driving more then not. Then the last couple weeks it sat more as my Impala was put into the car rotation then the stupid stuff started. So it is going to get driven and or started everyday when possible. I too was getting odd warnign lights, a hard start one time, etc.
Odd ball cars. HA HA HA

 

The only thing I can add to what Gus and the others is,ckeck your battery,if its the original it is time for it to start going downhill.If you are not driving it much that would compound a weak battery.Jags like their juice,if your battery is the original,its time to replace it anyway,try it and see if you still have the fault.

 

I agree, a low voltage battery will cause strange things to happen with these cars.

 

I'm having the same issue now. The start is also weak after a week or so sitting. After starting this goes away. As warmer weather gets here, I will be driving it more. 1 driver 3 cars, so they all don't get out as much as they should.

 

Drive your car!

 

Many thanks for all the replies, very much appreciated. I will let you know how i get on.

 

Great news chaps !!- whilst the dealer was moving her to the service bay she locked up with 'resrtricted performance' 'dsc systems fault' - banged in the lap top and traced faults to the fuse box / relay. New one on order for the grand price of £60 - she will be ready for collection tomorrow - Happy days..

 

Do you know what relay?

 

At that price it is probably one of the non-serviceable relays built into the fuse box PCB. I didn't look at top at what circa your MY is, but at around the 2003/4 MY Jaguar started putting several non-serviceable relays in on several systems with only a few special circuits replaceable.

 

Bad news - when starting still get 'dsc system fault' showing for a second or two, and then disappears......new fuse box and relay fitted... but no change --- driving me mad

 

Grazza,

Can you list Jaguar model and year? I'll see if I can help, but need to know if you're in the crossover year on the fuse boxes. I assume you are because they replaced the box.

 

^^

 

I went back to your first post to reread and see what I missed. What I am getting is that the car has failed to start and when this happened you get a cruise not available and restricted performance. Then a few minutes later the car will start and no codes. Now the Jag dealer has the car and he is unable to get a fault or have a no start. Is this correct?

A cruise control will appear if the brake switch is not working properly and should provide a failsafe mode but you say that was not one of them. Restricted performance is generated by MAFS, air filter, breather stub, cracked TB intake hose and the kicker the throttle body itself.

I would be looking at the brake switch and be sure that your air intake is clean and properly sealed. I would also be sure the TB is clean. I still think you have two problems.

My best guess!

 

Gus , Twice the car has failed to start, and infact just locks up. It will not crank nor are you able to say take it out of park etc. By returning within a few mins, it will start but will have 'restricted performance' 'cruise not available' showing. Within a few minutes all the warnings have gone and the car will fire up with no problem and drive normally. Several times when driving the 'dsc system fault' will be displayed and then after a minutes dispappear. Even when she fires up, for a second or two the 'dsc system fault' will light for a second ot two then go. Jaguar at lincoln have had the car now for about three weeks. No codes were found. They checked the battery - all ok. Finally last friday whilst moving it, she froze and they got a laptop on her which showed a code relating to the fuse box/relay. A new one was fitted yesterday, but according to the foreman when cranking he still gets the ''dsc system fault' light on for a second or two. Do you think these are two seperate isues ?, with the non start now cured by the new relay and fuse box, and the dsc system fault display not connected ? - getting a little tired of this saga i have to say - thanks in advance

 

Grazza,

First, I take it this is a RHD European model? If so, everything I add is to be taken with caution because often the electrical configurations are different among different country specs and I only have experience with NA specs.

 

Ieeyy! Somehow I hit return and my message posted before I was finished, so continued:

The shop (Jaguar shop?) diagnosed a failed starter relay which is non changeable in your MY. Only the whole circuit board can be swapped out which is integral to the fusebox. But, I am guessing that was only one of two or more problems you're experiencing.

Don't overinterpret the fault messages as multiple problems though. Cruise control not available accompanies a restricted performance message. Cruise control is disabled as a safety function since the ECM is in a default mode because of one or more sensor feeds, input or outputs, are out of range. DSC faults can also display as a dependant or subordinate fault.

At this point, the only advisement is take it back, let them continue the diagnosis they've started as we'll all be really guessing at this point. The restricted performance, even if extingushed, should leave fault codes. They've started a process of elimination, and they need to complete it.

 

Correct - I am in the Uk and so a RHD model - fully noted your thoughts/comments for which i thank you. Car still at the Jaguar shop, so i guess i have to leave it to the experts !! - Promise to keep you updated.