Dear All,

I am driving a 2014 XJ (8 speed gearbox) and have quite the 'X-File' on my hands with regards to these 2 faults - Gearbox Failure and Adaptive Dynamics Failure.

The background was that I did a transmission oil and filter change back in May 2019 at 48,000 miles.

This 'X-file' on my hands is further exacerbated by the fact that these 2 faults - Gearbox Failure and Adaptive Dynamics Failure only surfaces under these 2 conditions:

1. The vehicle is driven for more than 45 minutes.

2. The vehicle is driven fast consistently at speeds above 90 miles per hour.

When these 2 conditions are met, there starts to be an audible winding sound whenever you put the foot down on the gas pedal and thereafter, these 2 errors appears in the instrument cluster:





Also at this point in time, the rotary gear selector will get stuck in 'D' but the light indicating which gear you are in will not be lit up. Additionally, you will not be able to turn the gear into 'S', 'N', 'R' or 'P'.




With all these faults present, the car is still able to drive except with the following observations:

1. Drive become sluggish and the whining sound is audible whenever you step on the gas pedal.

2. When the car comes to a complete stop (example at the stop lights), the car is very slow to move off from stationary (despite stepping more on the gas pedal) but once it moves off, the drive becomes like point # 1 above again.

To recover from all these errors:

1. At a safe location (need to choose carefully as the car is not able to go into reverse since the drive selector is not working), press off the ignition.

2. Pop open the bonnet and then close it (not sure if this helps but that's what I did).

3. Now, power on the ignition again.

4. At the Drive Selector, you will see the indicator for 'D' is now blinking (note that the gear selector has been in the elevated position all these while). The gearbox and adaptive suspension faults are also no longer present.

5. Now, turn the gear selector to 'P' position and then switch off the ignition. The gear selector will lower into position (as per normal operation).

6. Finally, when you turned on the ignition again, everything is working fine once more (no faults whatsoever) and the car drives normally.


Thus, the 'X-file' on my hands is that there has been only 2 occasions (in June and September 2019) that I have encountered these faults and that is when I go for a longer spirited drive out into the country. When I am pottering around in the city with the XJ (like 99% of the time) up to speeds of 60mph, it works like a charm and there are no gearbox/adaptive suspensions faults or whining audible sound encountered.


I am really at a loss what to do as this is an intermittent issue that only surfaces when I drive faster and longer which is really absurd. The fault code reading from the OBD indicates a P0702 error but that really points to a lot of recovery solutions, some of which is a complete overhaul of the gearbox or to replace the mechatronic, both of which are costly affairs and seems like an 'overkill' especially when the car works absolutely fine 100% of the time in city driving.

Can the fine gentlemen in this wonderful forum please share some of your experiences with me as I have scoured through the X351 forum but it seems like nobody here have yet to face this issue?

Awaiting your kind advice and suggestions, thanks a bunch!

 

Not sure but I wish I could drive above 90 mph for 45 minutes! Well legally that is!! That must be a heck of a road?
I have been to Singapore but did not realize you had some open roads as it's a very densely packed place!

First thing is how old is your battery? If in doubt just replace it.
Second is have you read the codes and I mean all of them so a dealer will be required for that.
Thanks for P0702 but I think you might have some deeper codes that an ordinary OBDII reader will not see. Plus the TCM might be bad or it might just need reprogramming?
Again that requires a dealer.

But your correct that right now it points to the TCM or wiring problem to the transmission. Have you had a chance to check the electrical connector going into the transmission?
Might be worth taking it loose and inspecting it then re-installing it. As you found this is a very rare error code and I have never come across it on an X351 Jaguar.

Please post back if you find a solution.
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Whining noise sounds like hydraulic pump cavitation. My old Turbo 400 used to do it when fluid level was wrong. Based on your symptoms, I would guess that the fluid level might be too high. Too low is also a possibility. Then, of course, there's the fluid being the wrong viscosity.

Did you use the right fluid?

What changes on a long drive, vs. a short one, is fluid temp. Hotter = lower viscosity, also it expands, raising the level. Hence I suspect viscosity is too low, or level is too high.

 

Hi clubairth1, thanks for your candid response.

You are right on Singapore being one of the world's most densely populated places and probably the worst country in the world to be a car owner. Cars here costs an arm and a leg, you get to 'own' it for 10 years before its mandated by the government to become a heap of scrap metal and you can drive constantly in 'fear' with hidden speed cameras. Thus, my occasional 'exploits' of spirited driving are beyond the shores of Singapore and the locals from this region will definitely know what I am talking about.

May I check with you why you think that the battery could be linked to these faults? While my main battery is fine, my auxiliary battery (for the start-stop function) has been dead for some time. Thus, do you recommend to change out the auxiliary battery?

I will definitely take up all your suggestions in due course as I have yet to plan my next round of 'spirited' driving as these faults only surface given the presence of the 2 listed conditions. If I were to drive at 90mph here in Singapore any time soon, my next reply to you will likely be done with me behind bars in a prison.

 

Hi Mark SF, thanks for your advice!

I am quite keen on this theory actually as the only 'variable' performed on the machine before the advent of these faults were the transmission oil change. My mechanic is adamant that he used the right fluids which is shown in this link: Meyle ATF Plus 9

I have also looked through the forum and the owner's manual (which does not indicate the ATF to be used) and it seems like the recommended fluid is this:
If you are in my predicament, will you proceed with another round of transmission oil change as this is something that I am really prompted to try again! Thanks once again for your response!

 

The correct fluid is ZF Lifeguard 8. ZF makes the transmission, so it’s fluid is the safe bet.

There are some TSBs about wonky gear selectors. You just need to make sure you have the latest software updates.

Hope you get it figured out.

 

Hi Neodoerr, thanks for your confirmation of the fluid! Will likely go for another round of oil change just to be safe!

 

A low battery can cause all sorts of electrical glitches.

In my experience, if the main battery is low the stop-start function won't work. Because I'm retired and don't usually drive long distances that will keep the batteries charged, I always hook up my CTEK battery maintainer whenever I'm parked in my garage. I usually attach it to the primary battery and occasionally attach it to the stop-start battery. I have quick connect terminals attached to each battery to make it easy to switch between them.

See this thread for installation details: https://www.jaguarforums.com/forum/xj-x351-53/2013-xj-battery-maintainer-
installation-130801/

 

Hi Stuart S,

Thanks for your response.

My main battery is good but my auxiliary one is gone. Do you reckon that the auxiliary battery could cause this issue and I should have this changed out?

 

No way the auxiliary battery can cause issues. I completely removed mine years ago.

 

No

 

IMHO it's the fluid. This ZF 8 speed transmission is used in many cars across many manufacturers including BMW and others. My bet is you put the correct fluid from ZF Lifeguard 8 in and your issues will be gone.

 

"If you are in my predicament, will you proceed with another round of transmission oil change"

No, I would check the level first.

 

I'm having a similar issue with my 2011, which has the 6sp. It's probably happened on 4 or 5 occasions. Here are the conditions which seem to make it happen:

-Spirited driving above 90mph
-Usually while passing someone and trans kicks down
-I don't need to be driving long. Can be 10-15 minutes
-No whining noises

When the fault occurs, the trans will either kick down to say 3rd gear and then refuse to upshift or downshift - shift paddles stop working. OR will stay in OD even if i floor the accelerator.

I will get 'gearbox fault' as my only warning.

If I pull over and restart the car, the warning goes away and trans operates normally.

I've brought it to the dealer twice and they cannot reproduce the problem and they cannot find any stored codes.

I'm eager to get it resolved since I still have 20k miles of warranty left.

 

First thing as always with these transmissions is the fluid level. But you did not give us any mileage so we are guessing again.
As you know it's difficult to do and you need a lift.
Also has the fluid been changed?
Has the TCM been flashed to the latest revision?
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I am in a quasi similar situation. I don't get the tranny fault, but I do get the Adaptive Dynamics fault. I have looked in all the computers for a fault code and I can't seem to find any (granted, my code reader doesn't let me look at the Adaptive Dynamics module, only at the Ride Height Level Module) I haven't been able to find any codes to point me in a direction. In my case, most of the time it seems to come in when braking lightly or coasting. I get the message and I can feel the suspension stiffen up (from the active shocks loosing their signal and going to maximum stiffness). I do have 104K miles on the car and will be getting a tranny fluid change here in a few days. Hoping that this will somehow fix things (not sure how the tranny and the Adaptive Dynamic suspension are quite associated and one affecting the other). I do notice that mine is not as prevalent when it is cooler outside. Kinda like if I drive the car and get the message followed by me stopping and then restarting the car, the error will come on sooner (normally within a few minutes vice normally about 15-20 minutes into a drive). We'll see. Worst case, a trip to the dealership to see what they can find.

 

Well, follow up on my issue. It seems to have corrected itself. here is the best part, I haven't really done anything that should have fixed it. I did get the tranny fluid changed, but the fault came in a few times after that though. Then I also managed to run over a tree branch (fell out of tree directly in front of me, it was either a ditch, going head on with a large truck, or hitting the branch). The problem seemed to go away after the tree branch. The only other changes were the temperature outside is about 10 degrees cooler than when I was normally getting the problem (not seeing this as a potential problem). and I had some people in the rear seat of my car for a few trips. So, if someone has an idea, I am all ears as to what "the fix" is. maybe reading the codes in the tranny will show something. Granted, I would think that codes in the tranny would light up the CEL (which it is not lit).

 

Hi All,

A final update to this issue and well good news!

The weird issues plaguing my XJ are gone!

So here are things I did:

1. Change battery (it was due for a change), but not 100% sure it attributed to resolving the issues.

2. Replace the transmission oil again with the ZF Lifeguard 8 which is the OEM for the 8 sp gearbox.


And voila, I have made at least 4 trips where I drove up to speeds of about a 100mph and all is fine (no more stuck gear selector and sluggish engine performance).

So if any of the XJ owners here are planning a transmission oil change, save yourself the hassle and only use the OEM ZF Lifeguard 8!

 

That's what I used along with a new OEM pan and bushing. And no problems.

 

Just one additional question?

Does the 8 speed have the same sealing sleeve leak that the 6 speed ZF does?
I ask because the 8 sp fluid change kits do not include the sealing sleeve but they still contain the improved steel pan bolts. So I know the pan bolt problem still exists on the 8 speed.
So far at 42K miles I see no leakage on mine yet.
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