The dealer wouldn't have as much influence as ZF would have...but I doubt it, since any ZF documents always show the same valve body for the 6hp26.

 

The P0735 came back on after the fluid change. Once I can figure out how to unlock my sdd I'll try the re adaptation procedure and if that doesn't work I'll have to look in to a new valve body or trans.

is The CTSC - ZF Parts the best place to buy an OE ZF valve body?

 

CTSC is one of the best. Many on the forum have ordered parts from them.

 

I reset the adaption, its almost complete but I don't foresee my issue being resolved. I have noticed the trans acting normal before it gets to normal opp temp. By any chance did you try the trans additive before you changed the valve body? How many times was the fluid changed after your problems started but before the valve body was replaced?

 

I never introduced the additive. Dealer replaced the fluid after doing a pan and filter change at 82,000 miles. I again changed the fluid at 137,800 miles with ZF Lifeguard 6, checking multiple times for the correct level vs temperature. I would estimate symptoms started appearing around 140,000 miles, but I have little belief that my fluid change was actually a contributing factor...especially when it led to a physical valve body issue. My mechanic didn't find the actual, definitive factor, however. I can't recall if the solenoids on my VB remained...probably did, and the donor VB solenoids were left attached. The individual valves themselves, other than the new sonnax parts found in the group package, were also unchanged...just cleaned well.

Also, when most do the adaptations, we don't do that step by step procedure due to the detailed process, needing two people to really watch the laptop. Its probably a better tool, however. We just usually 'clear' the adaptations, and do the gear change under an RPM limit to a decel procedure - multiple times.

 

Your issue is the valve body. We have seen the exact symptoms time and time again on all 6HP transmissions. There are several issues that are leading to this trouble code.

Worn out main pressure regulator valve
Worn out TCC release valve
Worn out A clutch regulator valve and sleeve
Worn out E clutch regulator valve
Worn out shift solenoids

If the issue is caught early on and the fluid condition is still good then a simple valve body replacement will fix all of the symptoms you are having.

 

Revmax,

You say "We have seen...."

Who is "We"?

 

"We" as in Revmax.

Sorry, could have made that post a bit clearer in that aspect!

 

This is a great thread!

I have this 4-5 shift issue as well. Didn't think much of it as the shifts are all fine in the city driving I mostly do, and in the gradual acceleration (due to heavy traffic) highway driving around the Toronto area all is good and speeds of 80 MPH are easily attainable keeping he RPM below 2,800 and getting there gradually. As per the OP, the issue only happens when on the highway rapidly accelerating hard above 3,200 RPM. The squawk noise, occasional "gaerbox fault" message that goes away when car is restarted, and the dropping out of 'sport mode' when fault happens (though fault will happen on hard (full throttle) acceleration on the highway (full throttle from an on ramp speed of 45 MPH) in either normal or sport mode.

Talked to both a dealership and to an indy garage - neither had ever heard of this issue. Researched the issue on here and found the exact problem described better than I had described it, with the fix too - a ZF 6HP26 rebuilt valve body assembly - that RevMax says solves this issue, and, in his words, "We have seen the exact symptoms time and time again on all 6HP transmissions". Neither the dealership or the indy garage had seen this issue, and now I know exactly what it is.

My car is a 2005 XJ VDP, but also has the ZF 6HP26 transmission and does the same described problem.

Thanks!!

 

Do you have codes?

 

Do not simply assume that your issue is due to a worn valve body. Revmax was convinced that the intermittently poor shift-quality issue in my wife's 2006 XK8 this past summer was due to a worn valve body. I was not so sure. So I kept doing my research, performed a CTSC pan-and-sleeve replacement / Lifeguard6 drain-and-fill in mid-July, and then had the Greensboro Jaguar dealership perform a ZF adaptations drive cycle reset a few days later. Bingo - the intermittently poor shift-quality issue disappeared and my wife has reported nothing but butter-smooth shift quality since....

 

I am having very similar issues with my transmission on my 03 S-Type 3.0L with the 6hp26 transmission.

My symptoms are the 4-5 and 5-4 shift error code. My route home involves climbing some steep grades and this error only occurs when I'm stuck behind a slow moving (50-55 mph) vehicle going uphill. The error always clears itself if I pull over to the side of the road to turn off and re-start the car.

I have noticed a small trans fluid leak and am hoping this is the culprit. However with the mileage at ~140,000 I'm planning on installing a sonnax zip kit and new sleeve when I do the fluid and pan change this week. I'll also be installing new pan bolts.

Hoping this is all I need and no further damage has been done to the transmission.

 

I think Sonnax kit is for 5R55N - utterly different box.

 

You are right but Sonnex has now released a ZF upgrade kit too. They call them Zip Kits.
Zip Kits - Sonnax

I am so glad to see some after market improvements finally being made to the ZF!!
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Just a year went by...