I have a 2004 XJR, now at 181k miles. Did a trans filter and fluid change at 121k when we bought her nearly six years ago. Did another one last July at 176k, with a new mechatronic connector too. Proper Lifeguard 6 and filter each time.
Had one cooler hose leak at 179k and did the double worm drive replacement and re-topped fluid.
This weekend, in an attempt to cure the occassional whoop on upchange, I wiped the adaptations using SDD and reflashed the non-coded access to the TCM. On the test drive, gear changes were very harsh, and in hindsight it was not changing 3-4. Eventual gearbox fault light, which was cured after stopping on the off ramp and switching off and on again and we drove slowly home (3 miles).
Checked fluid again last night, after the car had cooled for a day, it was spot on. Did get an ABS light when I left off the brake while running through the gears with car up on axle stands. Cleared codes, and went for a test drive, with a navigator running SDD and watching the TCM adaptations drive cycle page. 3-4 was consistently the issue, got multiple acceptable changes for the 1-2, 2-3 and even 4-5, 5-4 if we went too fast, and even did get one or two changes 3-4, with no ticks though.
Battery is one year old, seems good. On charge today, and disconnected from the car. No ABS fault at the moment, air intake looks secure. Car is in California, so water/corrosion is not likely.

Any suggestions as to what to try next, other than a Demolition Derby entry?

 

The P0783 is a 3-4 shift malfunction, which would make sense with your 3-4 shift refusing to adapt. The FSM indicates that this code is a transmission mechanical failure (with no other details), which could be a solenoid no longer applying the clutch, or a physical defect such as a broken clutch pack. On other vehicles using this same ZF 6HP transmission the shift solenoids have been known to fail and cause shifting issues. Other people have found the seals between the mechatronic (valve body) and trans case have cracked/deformed and cause shifting issues. Some have found that replacing those & resetting adaptations will fix it.

That said, just the other day another forum member replaced all his solenoids and then could not get the 1-2 adapt to set. https://www.jaguarforums.com/forum/x...-shift-229120/ I'm by no means and expert on the ZF programming logic--it seems like if the trans does not see all its parameters set the way it wants, it will not adapt.

At this point, I don't think you can make it any worse by replacing the solenoids and trying again. This means dropping the pan and valve body to replace. You can replace the other seals while you're in there. However if the "whoop" shift has been occurring for a long time, the clutch pack or bushing damage may be done. It's your call if spending another ~$300 on solenoids + new fluid is worth the gamble. You may just need a full rebuild at this point.

 

3-4 shift issue is more than likely the E Clutch being done. Almost all instances of P0783 points to an internal mechanical malfunction.

Surprised this all started after clearing the adaptions and updating the TCM. Are you sure you updated to the newest flash version?

Did you write (by chance) the TCM version you updated to? You may have to go back in and check.

I helped the other member with the adaption issue as I have IDS. We wiped adaptions but he already had the latest TCM flash from Jaguar as validated by my IDS - so we left that alone.

1 - 2 would not adapt and latest update is that the specific upshift under light acceleration is rough, but functional.

We are leaning towards a solenoid was faulty out of the box or something wrong w/ the valve body.

Might want to consider swapping out the bridge and tube seals.

Tube seals (new) would slightly protrude out of the body, again very slightly...

Finally, did you measure the gap between the trans body and TCM harness when connected? Your looking at 2mm to 3mm max.

I've learned the hard way you can improperly seat the mechatronic seal (not fully) and the white tab will lock but not make full connections with the pins breaking electrical havoc..

Just some thoughts...

 

Hi guys,
Thanks for the replies.
I was using DVD130.03 v.109 of SDD, so not that new, but think it is the same TCM flash that I have used before. I did not write down the file used to update, but could go through the whole routine again to get back to that page?

I could consider trying to upgrade to a newer SDD on this laptop, must have a spare drive lying around to swap in and set everything up again (do not want to risk upsetting the working image I have now - or I guess I could image the HDD and then try upgrading).

Solenoids and seals and new fluid sounds like something I can do in my garage on axle stands, swapping in a replacement transmission is more than I am able to do these days.

 

Don't bother V130.03 has the latest TCM flash version for sure.

 

Rats!

 

A little research and a little thinking and I am at this point:-
The transmission was working reasonably well before I rest the adaptations, just the occasional whoop, it now seems to struggle with only 3-4 change and, if pressed, does get into 5th and 6th and drives just fine, then will come back down through, 6, 5, 4, 3, 2, 1.
To me this suggests the clutches etc are working, just something with the 3-4 shift?

So, if I drop the pan, do not find bits of metal in there or on the valve body, then maybe it is worth changing the solenoids and the rubber pipe seals and square mechatronic rubber seal, along with another filter and new fluid?
Or am I being optimistic and there is just too much wear in the mechanical parts and while the old adaptations had adjusted over time, new ones will never catch up?
I will readily admit my knowledge of automatic transmissions is pretty much non-existent.

 

That's a tough call to make... I'm sure abonano can correct me if I'm wrong, but (short of finding metal debris in the pan) I think the only definitive way to know what's broken is a complete teardown of the transmission. Obviously not practical. But if you spend $500 on new solenoids, seals & fluid, then find out you're no better off, was it worth the cost? If you plan to keep the car and rebuild the trans either way, I would go ahead and try new solenoids. Worst case in that scenario if the trans is no better, you need a rebuild but already have new solenoids to use.

 

mhamilton is correct. In a normal operating trans you will find some normal wear on the magnets - but anything that can be seen with the naked eye is a show stopper meaning there is a mechanical breakdown somewhere in the trans.

Again, the E Clutch is usually the first to go and the whoop sound is an indicator. Now, if you used any other fluid than LG6 or Mercon SP the friction modifier may have been missing causing the whoop, but if it has been happening for a while the clutch may be done and resetting adaptions made the hidden issue surface.

Now, it may be valve body or solenoid related.

Personally, when I had my P0783 on my other X350 NA - I changed the fluid, filter, reset adaptions and reflashed TCM. Made little difference.

I went back in with new fluid, good, used valve body, TCM and solenoids and swapped out bridge and tube seals and reset adaptions again.

Now, in my case I could never get the trans I to 4 and up in auto but could in manual. Ultimately, in auto I would have to let my foot off the gas at 30mph, let the trans slip into 4th then she was good.

I wound up trading the car for a new lease for my wife.

Just sharing my P0783 venture...

 

Hmmm, so research brings the usual mixed bag/two sides to every story of people sorting this with only solenoids, or with valve bodies and solenoids (mainly because they changed all at once, and did not determine which parts were essential) and others that never cured the issue. It really comes down to how lucky do I feel, doesn't it, how much enthusiasm do I have for another big repair on this car?

FYI, car has had only ZF fluid and filter the two times I changed it, 120k miles 6 years ago and 175k miles 6 months ago, so no reason to suspect it has had the wrong fluid.
Knowing me, I will likely gamble on the middle option, new solenoids, fluid and filter.
Car is not worth paying someone to refurb the box, or even install a used one for me, and I am pretty sure I cannot manage it myself on the floor of the garage, so parts swap, or sell as is.

We are off car hunting today, might not be a Jag we bring back, wife's choice. My daughter is still enjoying her NA 2004 XJ8 though, so will have at least one in the family for a while.

 

Hey Cooldood. Dealing with my own intermittent P0783. Maybe happens once every 2-3 months. Flushed fluid, changed bridge and tube seals with new filter. No silver in the pan and not too much sludge on magnets. No codes thrown since, but thinking about the valve body rebuild with Sonnax dampers and new solenoids next. Curious to learn what you ended up doing on your cat...

 

Hi 04XJR
I ended up selling it on to someone with more time, patience and 4 post lift.
I do miss it, the XJR is a different beast to the n/a version, but with transmission problem, fading paint, a pressing need for new suspension bushes, etc., etc., it was too many problems for me.

My daughters XJ8 got crushed by a falling tree while driving, we bought her another one.

 

99 times out of 100 when that code is flagged with full fluid the transmission is done

if your 3-4 shift is anything but impeccable the overdrive clutch is on its way out. do not clear adaptations or you will be stuck

either way a rebuilt valve body will be a good purchase if you put a used unit in