(mistakenly posted in XJ forum)
Hi, I've searched the posts for gearbox fault and found some under transmission failure. I have a 2003 XK8 coupe with 61,000 mi. in Northern Virginia. (I don't know what model trans I have and if it is came as Mercedes, Ford, or BWW.)
The posts are helpful but sometimes seem inconsistent.
I appreciate getting suggestions to clear up my confusion decide on remedies. Trying to decide to repair parts, rebuild, or replace transmission, to have fluids drained and replaced every 60K, and to have car towed to transm specialist.
My symptoms 1. gear box fault three times in the last 6 weeks when going slow around a turn or up an incline.
2. sometimes prior to the fault and sometimes with no fault, harsh shifting (1 to 2 gear) with a sudden surge.
3. At about 55k had transmission pan and seal replaced due to leak
4. Waiting to hear from dealer (Rosenthal at Tysons Corner, VA) about error codes; battery condition, condition of ECM, TCM, and MAF (what is that), fluid level, relay, electrical connections, ABS connector, A drum, and if magnets are covered in metal chips and shavings.

Solutions I read in posts:
1. reconfigured using the Worldwide Diagnostic System (WDS) with software release JTP
2. battery disconnected for a period of time long enough for the ecu's memory to be lost.
3. Drain and replace oil- posts about oil include ZF Lifeguard 6, jaguar dealer oil, Valvoline Maxlife NAG1 rated, Valvoline Highmileage,, ATF +4 fluid
Not sure which ones are ok with Jaguar or transm manufacturer (how do I check).
4. If pan is replaced, replacement screws use a larger torx head a #30 and a generous amount of anti-seize compound.

So how do I select a fluid, decide what type of repair- replace broken or rebuild, what fluid, what tests to decide? Jaguar said I could open a case, ask for case specialist 800 452 4827, ask for assistance to cover some costs since I am a long time owner and have owned two. Has anyone had success with this or from reporting to the NHTSA (seems like there is a safety issue if car can surge suddenly)?

 

Your 2003 XK8 has a 6HP26 transmission made by a German company called ZF. This transmission is also used in BMWs and other vehicles. The confusion stems from two other transmissions in use on XK8's/Rs depending on model year.

The harsh shift may be curable with a reflash, but the fault likely points to another issue. It could be as simple as low fluid due to another leak or incorrect fill when it was serviced at 55K.

Torque converter failures are are a known issue for the early (ie; 2003) version of this transmission.

Rosenthal is well equipped to diagnose this, but you may want to consider an independent shop to save money if it is a major issue. London Auto in Falls Church or English Auto in Odenton MD should be able to do this work for less.

You can open a case, you never know, but I doubt you will get very far on a 10 year old car out of warranty.

 

For an S-Type with same box I'd ask if there's any chance the battery is failing. Upsets engine which in turn upsets autobox.

 

Agreed. Always start with the battery. There have been reports here of owners paying for transmission rebuilds on an S-Type when all that was actually needed turned out to be a fresh battery....

 

The manufacturer, zf, said they now recommend replacing the trans oil every 60k, but not flushing.
How do I tell if I have the 6HP26 transmission or 5 H? The j shift pattern on the console goes from 2-5 gears.

 

Whitexkr already replied stating that on your 2003 it is a 6hp. As well, the J gate for the 6 speed unit goes from 2-5, on the 5 speed cars it goes from 2-4.

For what it is worth, if you had the pan and seal replaced at 55k miles due to a leak, then you have had the fluid replaced already.

I have never read where a 6hp had an A drum failure like the 5 speed unit do, stop worrying about it.

Depending on who did the pan/seal replacement work, you should either be comfortable and confident that the correct fluid was used, and the correct procedure to fill it with the correct amount of fluid was done. If a reputable Indy with experience with these was used, or the dealership, then you probably are ok; it should be good. However, if there is a chance that the refill procedure was not followed correctly, your fluid could be low, and or the incorrect fluid used. If that is possible, get it re-done.

Regarding the harsh 1-2 shifts, this could possibly be nothing more than a TCE reflash, as it isn't too uncommon on the 6hp, or it could be related to the above if that's really an issue, but I wouldn't get all hung up on it at this point.

 

Mine did this and the rest of your symptoms , the fluid was 1 liter low,I hope they don't lie to you.

 

Low can be due to not following the proper fill procedure (or a leak, of course).

 

Final (I hope) diagnosis for the 03 XK8 gearbox fault and harsh gear 1-2 shifting:

10/30/13 shop visit: Original dealer diagnosis- replace transmission with rebuild- $7,300.

Based on comments from this forum and JCNA Forums - Jaguar Clubs of North America,
I asked for battery check and recharge.

Dealer tested battery- low charge, cells ok. Recharged and warning went away.
Reflashed TCM and PCM
Warning gone, but harsh 1-2 shift
Cost $130

12/5/13 shop visit: dealer says battery would not hold charge. New battery. (Said maybe tester used before was faulty.

Re-configured existing ECM
Check fluid level and color- OK
Says no codes or warning.
Shifting ok.
Do NOT need trans rebuild.
Pick up car tomorrow. Cost including battery $230.

 

Drive fairly gently and avoid Sport mode for 200 miles and you'll probably get better shifts (TCM has to relearn after a reflash and PCM after a battery change).