Posted this in the XK8 forum, I am posting here because some other models have the same tranny. Got a gearbox fault code P1722 (OSS sensor). Checked the sensor, wire
to TCM etc. OSS ohms out at 333 ohms (same as TSS sensor). Swapped the TSS &
OSS, cleared the code, changed filter and fluid. Car pulls fine in
reverse, but stays locked in 4th gear (trans ratio 1 to 1) when the
fault trips. Car will rev to 1500, trip P1722, set the gearbox
fault and go to 4th gear. I have a hard time believing 1st gear is
mechanically busted due to reverse pulling so strong. I thought
usually 1st & reverse are on the same clutch pack and drum (reverse
using the planetary gears after the band holds the drum), does the
ZF 5HP24 work that way? Anyone else seen this? Aamco put their
scanner on it and thinks a solenoid may be sticking or the TCM is
malfunctioning... Any ideas?

 

Having seen this same scenario on more than several occasions, including my own car, I would think it's a cracked drum. I highly doubt it's the TCM if it didn't trigger other DTC's.

 

does anyone have an electronic copy of the ZF5HP24 repair manual? Want to run through the trouble shooting guide.

 

It's the A drum, failed at the snap ring land. Hope to get the updated drum with the dimples. Clutches look good even with 80K miles on them. Theses transmissions are built to last (except for the A drums).

 

That's what I figured it would be. I've seen it too many times

 

BTW... If you ever do a transmission fluid change, I used the Mobil 1 synthetic that meets the ESSO spec. It's $9.00/quart. At that price you can change it every 30K miles.
I put a 5 foot long plastic 3/8 line in a 1 gallon bug sprayer with a plastic ferrule to seal it, that made it easy to push the fluid in and not as messy as the 1 pint syringe.
When we replaced the drum with the new design drum (stronger, heavier, has demples on the top), we measured the clutches, only .001 inch wear in 80K miles (compared to the new clutch thickness. The 5HP24 tranny is well built... except for the A drum.

 

remosusa - Are you a Jaguar mechanic and did you rebuilt your transmission your self? Where was the new design A drum purchased and what was the total cost of the transmission repair including the labor (also the number of labor hours to r&r).

Yesterday our 2001 Jaguar XJ8 started giving the "gearbox fault" and shifting into 4th gear.
I called a Jaguar Specialist near our home in Cheshire CT (Motorcars LTD - they have been repairing and restorations Jaguars for the last 50 years). They want $2600 for the repair. They remove the transmission and have a transmission repair shop make and install a new improved A drum, replace the reverse gear and reseal the transmission and send back your transmission to them in 2 week time period. Then they reinstall the transmission. They warrantee the repair work for 12 months/12000 miles.
They have been doing about 6 of these Jaguar transmission repair jobs per month for the last 4 years with no customer problems at all.
It seems that this is a good deal, the Jaguar dealers in Ct want $6500 for the repair.
Is this a good deal?
Is 12/12 warantee a long enough warrantee period?

We had a problem last month with the timing chain tensioner breaking causing the engine to run only on the 4 cyinders on the passinger side. Hartford Ct Jaguar dealer wanted $122 to checkout the engine fault codes and another $2740 to replace the left side timing chain tensioner along with the timing chain for the left side cams.
I have a friend who works part time as a mechanic mostly on Fords. I printed instructions on how to replace the timing chains on XJ8 I found on the internet. Our friend replaces the timing chains and tensioners on both sides of the engine, also replace the water pump while he had everthing disassembled. I purchased a Jaguar timing chain kit on the internet, also rented the tensioner tools from the same person on the internet. Total cost of the repairs for parts and labor came to $1954.

We owned this Jaguar since early 2003. For 6 plus years, it has always been regularly serviced at the local Jaguar dealerships. I could not believe that Jaguar service never
cautioned me about the history of the timing chain tensioner problems on this
vehicle year and model.

I filed a complaint with the NHTSA US Dept of Transporation and with Jaguar corp USA about the timing chain tensioners.
If enough of us Jaguar owners file enough complaints then maybe NHTSA will issue a recall. It is a very easy process to file the complaint online.
All you Jaguar owners out there, please take the time to file a complaint with NHTSA.

Maybe we all will be able to get some of our repair costs back from Jaguar.

 

i believe there is an ebay seller that has rebuilt A-drums. Gus and Visqousquirrel own XK8s and have, or are working on the drum failures. The parts are available at fairly decent prices.

BTW, remosusa hasn't logged on in 3 months, he may not reply to your post.

 

Recalls are for safety issues, not simply mechanical issues, FWIW. Timing chain tensioners do not pose a safety issue in most cases.

 

Although, perforce I am a 6HP26 man, on recent research into my autobox, I came across some information about the 5HP24. On no account are you to sit in the car revving the engine in either neutral or park. This is likely to write off the front clutchpack (I think that's the "A" clutch) due to excessive uncontrolled hydraulic pressure.
I give you this for what it's worth.
Leedsman.