Hi Guys, I really need your help with a "transmission fault" message that's hit me recently.

Some background info:
- My 02 XKR coupe has been sitting for 3 months while I was away
- Before sitting, the car drove perfectly fine. No issues, no codes, and transmission shifted perfectly
- When I returned, the battery was dead, and I replaced the battery with a new one

Symptoms now:
- When I drive the jag, I get a "transmission fault" message.
- The car continues to drive OK. There is no check engine light.
- If I pull over and cycle the key, the message disappears, and car drives OK. The message does not appear every time I drive the car.
- At first I thought this might be an error, but the message has flashed the last three times I've driven the car. For the first time today, the check engine light also came on. A scan revealed code: 0730: "Incorrect Gear Ratio".
- I have the correct MB transmission dipstick, and have checked the level, which appears to be OK (see image below). However I have gotten a spot on the driveway while the car was sitting, though I suspect it's coolant (as that also signaled a low and I had to top off about half the reservoir).

Does anyone have experience with these symptoms? I'm looking at these three options:
1. Change the fluid & filter by dropping the pan
- however, the current fluid level looks OK....
2. One member in a similar post mentioned:
"Jaguar now recommends clearing out trans adaptations and reflashing with latest software. Evidently it can become a learned condition in many cases and trans not needed."
https://www.jaguarforums.com/forum/x...-01-xjr-61501/
- Anyone have experience with this? I'm thinking it could be a software issue due to the battery change, and the fact that the car ran perfectly OK before it sat...
3. Get a new tranny
- This would be the last step, and considering the ridiculous shop rates in our overpriced Vancouver, this would seriously make me question keeping the jag...


Current fluid level after going from cold to a short drive:
(P.S. Is the MB ATF fluid supposed to be yellow-ish instead of red...?)

 

The TCM gets its information about wheel rotation from the rear abs sensor. This is matched up against engine rpm. If the information is wrong you would get a "Incorrect Gear Ratio".

As your car has been sitting, perhaps the sensor harness contacts have gotten dirty/corroded. There is always the question of whether the sensor itself needs cleaning as well.

In any case, the abs sensor data is the most likely cause of the message. Unless some benefactor installed a 4.11 LSD for you in your absence

If the battery was dead and the transmission adaptions cleared, you would be in learning mode. So, you might want to go read up on that as well.

 

Thanks for your answer plums!

I did actually clean the ABS sensors a few months back, but I'll go at them again and see if that helps.

If the shift adaptations were cleared, and I was in learning mode, would that contribute to the issues I'm experiencing? I've read up on this online a bit and I see suggestions to have the dealer clear and reflash the tranny. I don't understand why the TCM would ever need to be re flashed however, or is this something more common the Jags?

 

I've gone through the incorrect gear ration saga, but may not even be related since my tranny is the ZF6hp26. Dang that fluid looks nasty, I'd get a fluid change and clear the adaptations, and do a proper education to it.

When I did the adaptations to mine, even going through the learning procedure, I managed to set three (3) gearbox faults in the process. Its easy to go outside of the RPM parameters vs shift points of the learning method.

 

Don't have an answer here for you, but for just to be sure, have you checked the oil temperature when you measured it and was the dipstick measurement with the engine running?

Yellowish isn’t an issue, better then black and smelly, however if your oil has never been changed, after 10 years of service it might be a good time to change it as well. Or you could have it checked with http://www.blackstone-labs.com/, but I would change it regardless.


Here form a MB forum:
http://www.peachparts.com/shopforum/attachments/tech-help/40772d1170130687-diagnose-repair-p0730-722-6-mystery-fault-po730-1.pdf

You might want to check the wiring harness as well, make sure it’s clean and not oily.

 

Thank you guys.

I've done about 300km since the new battery and (knock on dash) I don't seem to be getting the transmission fault message anymore! Sounds like it was a byproduct of the battery change and the adaptations re-learning process you guys mentioned.

I will be changing the ATF fluid shortly, and will post up some pictures when I do. I have the MB 722.6 filter, gasket, harness connector, MB dipstick, and IR thermostat gun ready. I also just ordered in 14 qts of Shell 134 ATF fluid, per MB spec 236.14, and I'll plan on doing a fluid change per writeup I found on an MB forum (5 quarts fill, (3 quarts drain & fill) x 3 times). Thanks for your input!

 

Valvoline Maxlife Dex/Merc from Walmart at something less than $25 a jug is what I used. There was a Mercedes training document that specifically listed it as suitable for the W5A580.

A brass hose barb fitting and some vinyl hose from Home Depot connected to the transmission cooler outlet let me flush directly without the bother of add and dump. Just drain the pan, replace filter, clean pan, refit pan, pull the fuel injector fuse and then crank the engine in very short bursts while refilling the pan until clean, clear red ATF runs out. The end of the hose has to be well anchored in the disposal container or it sprays all over the place. The pump runs *FAST*! If you have a helper, you can have the helper refill the pan continuously.

An adequate dipstick can be made from a bicycle brake cable if you know the dimensions. Do not use shrink tube as length markers at the working end as it will slip off. Instead put it at the "handle" end and just bend the cable ends together to compare the level.

There are two DEX/MERC formulations ... make sure you get the MaxLife.

 

Wow, that's an awesome tip, I didn't think of that! I'll post an update and some pictures when finished!

 

I edited while you were posting. You might want to re-read for the changes.

 

Don't forget to check or replace the electrical connector sleeve as it is a known leak point. Pan magnets are cheap at the Mercedes parts counter.