1999 XJ8L
On the way home from work pulling onto my street that has a incline to it. car rolled to a stop and would not move at all. Dashboard lights lit up and the message center says "gearbox fault,engine failsafe mode,stability control failure"
I'm on a hill and the car will not go forward. When I gave it a little gas it had a small vibration. So I put it in reverse it felt like someone hit the front of the car it jerked but still would not move. now I'm on a what 5 or 8 degree incline with no brakes on it still won't move. So I turned the car off and restarted it. There were no messages or check engine light on. So I put in drive and it shifts smoothly and I pulled in my driveway and turned it off went to my tool box, got my code reader and plugged it in to get codes. The only thing on the reader was the p1111 code system pass thing nothing else. On the way home the car shifted fine no hard shifts or anything other than no a/c. But that's a thing for another day.
So what should I do next and is it possible to drive it for at least one day till I get my truck back? Or am I going to have to drop the transmission and tear it apart?

 

I suspect an electrical issue, such as weak battery or poor power and ground connections.

 

The A drum has a different way of tell Ing ypu it is dead. R would go in ever so smoothly.

 

I drove it this morning and no problems. When I drive it home I'll tighten all of ground terminals and see if that helps.

 

Don't just tighten them. Disconnect and clean. If there is corrosion the problem may come back.

 

Hi Belmon,

I think RJ is on the right track with his suspicions of an electrical issue.

You need to do more than tighten the ground terminals because they tend to corrode over time. You need to remove the nuts and thoroughly clean the threaded studs, ring/eyelet terminals and washers. I use a small wire brush and a good zero-residue cleaner like electronic contact cleaner spray (MAF sensor cleaner or brake cleaner will work too). Allow to dry then reassemble and snug the nuts securely but do not overtighten, which can damage the threaded studs or their connection to the body. If I remember correctly, the Transmission Control Module uses the same ground point as the Engine Control Module on the left front inner fender in the engine compartment. Check the ground locations in the Electrical Guide, which you can download here:

Jaguar X308 Electrical Guide 1999

While you're cleaning grounds, don't forget the two ends of the engine ground strap.

I would also recommend that you clean the electrical connector on the transmission itself, since it can become contaminated with oil or other grunge.

And while you're at it, it's also a good idea to clean the battery power connections such as the false bulkhead stud on the right front inner fender. Just disconnect the cables from the battery before you do any work on the power connections (and clean the battery cable terminals while you have them disconnected).

Please keep us informed.

Cheers,

Don

 

A regular generic code reader will not show transmission codes - my 2002 XK8 showed only the P1111 ready code. I also tried my laptop-based software with the USB-ODB adapter but didn't get anything unusual there either.
However, when I took it to my friendly transmission shop their reader showed a whole bunch of transmission fault codes indicating a badly worn transmission. Most reputable transmission shops will read the codes for you for little or no payment, and then you will have a better idea of what you are dealing with.
For what it's worth, when my A-Drum failed it was preceded by grabbing or jerking when shifting up and when it failed completely I was left with no forward gears until the engine hit about 3k rpm when it lurched with a nasty bang (which I didn't repeat), but reverse worked perfectly.

Best of luck with it.

 

Well on the way home got to the intersection to the street I live on it has about a 10 degree hill. Right when the light turns green the dash says engine failsafe mode gear box fault. Ok I'm just 400 feet from my house just need to go up 2 small hills and back the car in the garage. Right when I hit the hill the car stops and will not move. I tried turning the car off and restarting it the faults are still on the dash I put it in drive and heard a loud thump the car jerks and won't move at all. Call AAA to tow the jag like 250 feet and roll it in the garage. Tried restarting and try reverse, nothing, try drive, loud thump the car jerks and won't move. Codes are p1121 pedal position sensor A circuit range/performance this code is on twice and code p1111 system pass witch is not a bad code. Right now I will try don's and rj1237's recommendations and clean the ground terminals. But I will have to drop the transmission to replace the rear main seal at some point in the near future because I do not like oil leaks.

 

Also when the car is off but the key is in the on position the dash says failsafe engine mode, stability control fail. When I turn the car on its the same message but with gearbox fault also.

 

Well I cleaned the ground points using the guide Don gave me and the car still won't move. same messages on the dash as I said in the other post. Car still does the same thing when I put it in drive a loud thump a jerk then nothing, reverse does nothing doesn't feel like it shifts to reverse at all. So I'm guessing the transmission is shot. I'm going to see about the other code p1121 for now. Any suggestions is very helpful and welcome thanks.

 

Hi Belmon,

Did you clean the electrical connector at the transmission?

It would be worth checking the cable that attaches to the side of the transmission for stretching. Some members have also reported discovering that the nut (part 7) that secures the cable bracket to the side of the transmission was loose or missing:


It would also be a good idea to check the fluid level in the transmission and to inspect the transmission and bellhousing for any signs of a fluid leak.

Please keep us informed.

Cheers,

Don

 

There is a Technical Service Bulletin on code P1121 relating to an improperly adjusted throttle cable. Googling it also returns it being a fault with the throttle/pedal position sensor. If you want to check it out, make sure you include "Jaguar" in your search as P1121 on other makes of vehicle return completely different faults.
I would imagine that the transmission may well have issues if it is unable to get an accurate reading on the position of the throttle.

 

Martin,

Thanks for that helpful post! Your eyes must be a lot better than mine. Somehow I had overlooked the fact that Belmon had reported P1121 is flagged.

Belmon,

You can download the X308 Diagnostic Trouble Codes Summaries guide at this link:

Jaguar X308 DTC Summaries 1999

Here's a snip from the page that includes P1121, giving possible causes of the code:




Cheers,

Don

 

Ok so I went through just about every connector that I could see and get to and re did the ones I did Friday night. And I'm talking about from engine to differential. If it was outside of the car it got cleaned. After that still nothing car still did the same thing. The next thing I did was remove and reinstall the fuses and relays in the 2 boxes on the driver side fuse boxes. And I'm guessing that fixed it because the lights and that one code went away. And the transmission shifts fine now. So thanks for all of you're guys help and recommendations on what to look for.