So i currently own 3 and have had 4 total jags. 3 xj's and an x-type. 3 of the 4 have been great . Minor issues here and there but all resolved pretty quick and somewhat inexpensively. With my wife envious of my 08 vdp, she wanted one of her own . So when we spot an 04 base xj with 49,000 miles on it about a year ago we snapped it up. Was owned by a gentle man in 60's and was in great shape

I have always read about the jags which have problem after problem and always dismissed it . But a year later and constant problems i feal i have my hands full.

We have a new problem this past month i have been trying to fix and i can at least say its consistent. Heres what she does;

Wife drives reserved usually but one day when merging on highway and had traffic closing quickly she floored it. The car jerked , slowed down flashed "dsc not available " and then "transmission fault" and oddly enough the windshield wipers when on and the lights kind of flickered. since the car basically lost all power/ acceleration she about got crushed by oncoming traffic. so needless to say she is a bit scared to drive it .

The car will continue to show the "dsc not available " and then "transmission fault" on dash and drive pretty normal. feeling a little sluggish but definitely not limp mode. as soon as the car is shut off and immediately turned back on all codes go away and the car drives fine . no codes or dash lights / messages whatsoever


She told me what happened so i took it out for a spirit drive accelerating to 3/4 throttle and all seemed fine, chalked it up as just a cat scratch.

But to do full testing i decided to do very aggressive driving .

1st test. performed a break stand burn out ( testing purposes only). turned off dsc , foot on break , revved it up to about 2k and boom. car bucked and did all the symptoms described above exactly

So now i realize she may be right . I shut the car off, restart and once again, no messages , no codes and car drives great

2nd test . decided to just floor it, and car rolled forwarded seemed like a foot and boom, bucks and does every symptom described above exactly.

I did that 3 more time and now realize, houston , we have a problem.

Investigation led to TPS sensor on throttle body or throttle body.

fix 1 choosing the cheaper of the 2 options i ordered the new tps sensor and after the car did exactly same problem

fix 2 decided to install entire brand new jag oem throttle body. feeling confident this would fix it i jumped in and boom, same exact problem

So now i am just confused and frustrated and do not want to bring it to the dealer just because . i enjoy the satisfaction of keeping these cars on the road with my 2 hands and my cash in my wallet.

I fear my next step is the dealer though unless the wisdom of this forum can help me out, which it has in the past.

Hoping the symptoms are unique and consistent enough that someone has a clue. like i said , it acts the same way 100% every time right down to the 2 swipes off the wipers

any clues? Will mail the responder with the fix ,a bottle of their choice!! even if that means shipping across the pond

 

Check out a local "chain" for auto parts to see if they will read your codes for you, if you don't have a scanner. What are your miles at now/ With only 49,000+ miles probably many things have been neglected and should be dealt with. I would like to know the fuel pressure and would probably change the fuel filter. Very easy to do and can cause problems like you describe. However, I would check the battery and the usual grounds because as the engine moves, the wiring harnesses could move also. Making a condition occur that you would not see when driving is not "spirited". The codes will help a lot. With more than one newer model Jag I would get a code scanner. Good luck.

 

This post may be relevant but I have no idea, just sounded familiar, transmission and dsc faults with random performance issues:
https://www.jaguarforums.com/forum/x...-intel-203967/

 

If it were me, the first thing that I would do is to make sure that the battery connections are clean and snug, and check the earth grounds in the trunk (boot) as well.

 

Before swapping any parts, check the battery voltage. With the ignition in the OFF position for at least ten minutes, check the voltage across the battery terminals. Voltage should be 12.6 volts or higher, if not, the battery should be replaced.

Many of the electrical 'gremlins' chased on these forums are the result of a failing or weak battery. The warnings on the instrument cluster are often the result of low voltage or engine misfire(s).

Under no circumstances is the vehicle to be operated under conditions that cause the MIL to flash as catalyst damage is occurring.

 

thank you for the replies , hopefully we are getting somewhere

1. i do have 2 card readers. 1 is the standard autozone unit and it shows no codes before , during , or after the event
also have the laptop with SDD program ordered out of england. it seems to work great on the o8 but for some reason the software does not offer the same functionality on the 04. it does recognize the car though.

2. i will change out the fuel filter next chance i get as it is a basic item i should do as maintenance and is cheap and easy.

3. the battery is brand new , replaced few months ago. i know that does not prove it is good so will check voltage

4. earth grounds , what a pain in the *** these seem to be. i just went through what seemed like a 6 month nightmare with a failing fan that wouldnt kick on and caused the car to overheat at idle. turned out the ground for fan was corroded and after replacing that lug for 50 cents the fan worked like a charm.

i did not realize the grounds were also in trunk , i thought the only grounds were behind headlights. is there a reference that shows where all the grounds are , or at least which ones are common to check. what is the method for checking / verifying a ground. i am capable of electrical work but by know means skilled at any of it

the biggest thing i can say about this problem is it occurs at the very same moment every time based on throttle position. the car could be driven for ever so long as the throttle is not pressed halfway. this gives me the impression that this is not a problem that happens randomly but under exact conditions every time.

 

I had something very similar happen to me last winter. Just a wholesale supply of weird errors. Even the radio was randomly rebooting itself. The PO had replaced one of the ground lugs near the passenger side headlight, so I got the idea of cleaning the rest of the ground points. As I was putting the nut for G1 (near the driver side headlight) back on, the lug snapped under very little torque, so I drilled it out and replaced it with a bolt and nut. I cleaned the rest of the ground connections with a dremel tool as well. After that, all the weird gremlins went away. With everything I did, I'm about 99% sure that the problem was the ground lug that snapped so easily.

 

On my 2005 Jaguar XJ8L, the two earth grounds that I'm familiar with in the trunk are located just to the top rear of the battery and above the fuse box. Just follow the negative cable of the battery. Generally speaking, unless those earth grounds don't look particularly tarnished, just make sure that those earth grounds aren't loose. One thing that you should always remember is that when dealing with low voltages as in this case, the car electronics won't work particularly well at all with loose connections or bad earth grounds.

 

IMO the front wipers coming on are a clue.

+1 on the front grounds.

Position of grounds are shown inI the Electrical Guide - sticky on this forum.

 

I did not catch that the wipers came on by themselves when the events occur. Is your wiper control set to "Auto" for when it rains? I do not think the fuel filter would cause that. Odd that you are not getting any codes. What version of SDD are you using?