2003 XK8 needs a rebuild (internal failure according to OBD and a road test by qualified AT specialist), remanufactured or used unit. What needs to happen for a replacement to communicate with the existing electronics? would I have to take it to a Jag dealer to sort out potential conflicts?

 

Curious:- what are the symptoms and the attendant codes?

 

P0782, P0825 and P1646. If heading out to the Interstate in the morning all would be fine., but commuting though town with a lot of traffic lights and shift cycles....2-3 shift would get increasingly abrupt until GEARBOX FAULT. Stop/iIgn off/restart would get me to work in 3rd. Took it to a highly regarded AT shop and they said oil was 1qt down and they got an internal failure code from their scanner and suggested a rebuilt unit as they didn't want to get inside. At present I have not found a rebuilt one available-but would be around $4000. A few used ones around $1000-2000 and who knows? Car has 67K and had the trans oil/filter changed at 60K. What are the chances that once opened up, there would be a small and easy part to replace?

 

Seems to be a low mileage for a 6HP to give trouble. Here are the three codes:



I've done a quick forum search on P0782 and it could be a solenoid issue which shouldn't be a major fix.

P1646 not related and almost certainly the HO2 sensor gone bad.

What ATF was used for the oil/filter change?

 

Normally, things are taken a step at a time. Our transmissions (6HP26 by ZF) are generally considered reliable. I am not sure of the fear to open it up. The valve body is accessible from the bottom, no need to pull the transmission off the car.

Start with a deep maintenance: fluid, pan/filter, connector sleeve, tube and bridge seal. Check the fluid/filter for metal bits indicating true mechanical problems.

Look for out-of-whack items like loose reluctor rings, rubber coupling, etc.

Then do re-set of the adaptations (software procedure), maybe consider a full reflash with a newer firmware version.

Then look at either replacement solenoids or a reman valve body.

Check the code along the way.

 

^^ What he said. And as Michael asked, what ATF was utilized during the drain-and-fill?

 

Thanks-unknown to me ATF-but done by a well-respected indie shop. What bugs me is that over the years since that service, the car has been up on a lift for a few other fixes and no one mentioned that there was apparently a tiny weeping around rear seal that ended up losing 1qt of fluid (which the current AT shop had to add before road testing/reading codes). I'll have to check prices on solenoids and reman valve body and see if this shop has the time (or fondness for exceptional cars) to want to pursue the work!
_______________________
03-XK8
87-Porsche 944
94 Ducati 900SS
16-ZERO FXS

 

Try to establish what fluid is in there. It should be ZF Lifeguard 6 or properly equivalent, like Mercon SP (many recommendations on here for the latter).
Definitely not something off the shelf from Acme corp.

This post from JayjagJay will give you an idea of what it looks like in there:
https://www.jaguarforums.com/forum/x...7/#post2390381

 

That is part of the major maintenance. This is because that connector sleeve needs to be unlocked by pulling a tab accessible only when the pan is removed, i.e. when the fluid is drained. This is SOP for this transmission. FWIW, the fluid level on this transmission has to be set in a fairly narrow range of temperature (basically such that it cannot be filled any longer once a min temp has been reached, but not above a max). I believe the fluid level has to be "exact" for the car to work at all angles, etc. Hard to believe being 1 qt short would throw codes just driving around on normal roads...

From memory, there were solenoid sets on eBay for less then $500. Reman valve bodies might be a bit over $1000. Maybe add shipping/core charges. To my knowledge, unless you see metal shards/filings in the fluid/filter, best assumption is that the transmission "internals" are fine, i.e. the transmission does not have to come off the car.

FWIW, ZF has a customer service team that can be called (Ericson Industries?) for advice. I am sure codes help. It is reputedly backed by real transmission techs that have been known to provide genuine help in the past, not some random rep reading off of a script.

Also, your ECM might put your car in limp home mode because of that O2 sensor error. I would definitely address that first.

Next, I would focus on the linear switch message. Start by moving the shifter around and see if the illumination follows the selection (D light is on with shifter in D, etc.). The underlying micro switches have been known to fail. In town, drive in "5" instead of "D" and see what happens. Second, that shifter assembly requires a somewhat tricky alignment when put back together. Maybe someone before you messed that up. Last, I believe there is a "cable" going from the shifter to the transmission and is attached with small hardware known to come loose. Yet another $0 thing to check. FWIW, you might want to secure access to a proper JLR code reader, not only for the codes but also for the ability to read live data (gear switch values, road speed, etc.).

Best of luck, keep us posted.

 

Yes Eriksson Industries out of Vermont - they may have a rebuilt for swap Jaguar

 

sigh....Transmission shop says codes and test drives do indicate significant internal damage requiring a complete rebuild and his experience with ZFs is parts can be N/A or too long to get for him to tie up his space. Barrett lists reman valve body as no longer manufactured but Eriksson says ZF has them new...maybe... No rebuilt units available anywhere, so looking for used. Any model substitutes work? I see more 2003-06 XJ8s than 2003-06 XK8s (only a few of those listed out there) or Land Rover!? I'm thinking that these specific units are "no longer supported" and will have to
depend on used. BTW, I did do the shifter troubleshooting.

 

Call the ZF tech support guys in Chicago at (800) 451-2595. Ask for either Steve Jaffe or Joe Laubinger. I expect that either one of them can help you source parts....

 

So the shop doesn't want the job.

Sorry, codes are only indicators to problem areas. Without a sensor on every moving part it's not possible to be that definite. OK, experience counts for a lot, but I'd be opening it up before I'd pronounce 'significant internal damage'

These boxes are in lots of different motors. Even Mrs H's X5 has one...

Definitely speak to ZF

 

Hey, Alto!

I went through this a couple years ago and found a source ( https://www.wittrans.com/ ) that sold me a rebuilt valve body/TCM unit - pre-programmed to the car's VIN! Installed mine and it's been flawless ever since. Here's the thread I posted here - read through as you like, but there's a lot of good input in there from several folks here.

https://www.jaguarforums.com/forum/x...estion-229263/

After a year and a half and a couple thousand miles it's still shifting perfectly! Give the guys above a call - hopefully they can help.

Mickey

 

I'm taking the car back from the transmission shop and found two NE restoration guys with extensive Jag and Mercedes experience for diagnostics. But first, it dawned on me that this all started after two related services-having front discs/pads replaced and mounting winter rims/snow tires. I'll have those areas checked out as well as replacing the left-bank upstream HO2 replaced...oh and also checking a possible vacuum leak that may be causing the slight rpm oscillation I get some mornings.
I'm beginning to appreciate the "dumbness" of my 87 944!

 

LOL

I wouldn't write it off yet. Good luck with the NE guys.

Note bank 1 is RHS.

edit: I don't think yours is the same issue, but take a look at this thread of razorboy's if you haven't already come across it. Things are not always what they seem:
https://www.jaguarforums.com/forum/x...7/#post1919626

 

Sometimes the first advice is the best and gets buried under piles of TSBs and forum threads. In the original "sticky" on AT woes, there is
Jaguar's diagnostic sheet that says the first place to look is a loose air intake hose. I did that and confirmed it was not loose and went on....hence this thread.
BUT whilst poking around looking at the O2 sensors due to a fault code, found a crack in the under side of the accordion pleats of the air tube! A wrap of aptly named duct tape (and a replacement tube on order) and a hard reset of the ECM-all seems OK! No gearbox faults or O2 sensor codes. The AT seems a bit "tender" but I assume it is having to readapt to less confusing information coming from the ECM.
Fingers crossed.

 

Well done. The black plastic OEM ducts are indeed susceptible to cracking and splitting on the underside of the accordion section after baking in the engine bay for a few years. I went through the factory duct and a replacement OEM duct before I finally got wise and ordered the aluminum duct kit from Mina Gallery in April 2019. Problem permanently resolved as a result....