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ANDY ! this post is 10 months or so old and will not open for me...would you be able to post it again?... I am trying to learn all possible before finding the right shop to open my ZF6HP26.... I thank you ALL for being active and helpful to my new community of enthusiasts; a tremendous help to me already !
It's the same as the one in post #19, that one works.
Let me explain my recent experience with LED brake light. After changing my regular brake light for LED, I found my 2006 XK8 sending a Dashboard message For check brake light. I didn’t install the resistance at that time so I said, I will just clear the message.
On weekends i went for a nice road trip and and found the beautiful Jaguar electrical nightmare! My transmission was not sifting At all while on D when leaving the stop sign. I had to shift manually or remove the Sport mode, then move up until 3000 rpm, lift the throttle pedal then it work.
Cruise control was not working either. So next morning I tought that all this happens after putting 2 LED brake light so I put back the regular 7258 bulb in place.
I went for a road test and suddenly everything was back in perfect condition. The gearbox was working as it is suppose even on Sport mode, Cruise control was working perfectly and the dashboard message was gone. So Jaguar is a very sensitive CAT to any electrical fault.
So be careful if you want to use LED bulb, you could find yourself with others issues that you had never planned.
Very interesting!. Clearly, the tinkering you did with new LED brake lights made the Transmission think vehicle was braking. The Transmission Control Module is fed status (Via CAN BUS) regarding the braking condition and will not enable ratio change-up if the brake lights are on. This is irrespective of engine revs and whether you are actually braking or not. So the brake light circuit is key.
As you know, when you depress brake, the pedal switch turns on the brake lights, but also, the system is looking for volt drop to check bulb health. It was this closed circuit that was somehow being fooled and affecting your Transmission operation!
In standard brake light set-up, the system is fail-safe with no affect to gearbox – but there’s one exception to be aware of in future. The brake pedal switch has a little built-in ratchet that can require resetting if the brake pedal has been pulled hard towards the seat, the ratchet will set and the brake lights come on permanently without the pedal being depressed. This situation will also cause the gearbox to not change-up in D-Drive (like your failure mode). So, if same Gearbox fault ever happens again, one check is to see if the brake lights are staying on all the time....
This is what happened to my 05 XK8 with 49,000 kms. Transmission wouldnt shift up most times and if it did into 2 it was at 5000 or a flick of the gas would also shift. I also had failure message of cruise unavailable and a rear light issue. When the ratchet is out of place the car thinks and acts like your foot is on the brake pedal. I was lucky and could at least drive the car but with mine the ratchet was just done and required a new switch where after all worked perfect. I did try a switch from a wrecker which was also faulty so be careful as the effects of the switch will appear to have a fried transmission so some people will just part out the car if it has high mileage. Best to go new with the switch,
I had not been here in a few years I do not believe, so most likely posting in the wrong place. With that my 2000 XK8 had a delayed engagement from park to drive and drive to reverse and again from a stop light to going. Not real bad but not right. NO codes!! Took the transmission out. Second time now...First was to replace rear main seal. Anyways I thought I needed clutch drum A. They are known to crack and trash your transmission. Turned out the valve body had a crack in it. Just thought I would pass the info on. This is on the top side of the valve body. You have to remove the filter and valve body to check it for cracks. I saw this same crack happen before, so some what common. Normally clutch drum A's upper cage comes apart trashing the trans. They make a more heavy duty one...
I've read through most of the messages on this thread, so I think I am on the right one. Had this 06 XKR since 2014. Had 28K miles on it then, 50K mils now, so not a lot of miles over the years. This issue has been happening over the past 4 or 5 years.
I've never had a check engine light or any other messages - except once very recently - a message that a rear light was out - turns out it was one of the rear fog lights. I didn't change the bulb out and never got the message again. Noting this because it was mentioned in more than one post.
Sometimes no issue at all in upshifting. But I did figure out that when backing up, if I came to a COMPLETE stop first, the car shifted better more frequently. Sometimes switching back and forth to sport mode helps. Neither always works.
No ABS warning either. I think ABS is working, but the car stops so well, hard to prove.
The LAST place I want to take the car is the Jag dealer -- at east not until I inform myself as fully as I can.
Also, the cruise control has never seemed to have had an issue.
At times the more I drive it the better it shifts. Sometimes, no. Sometimes start driving and it is fine, then pull away from a traffic light and I have to manually shift. Sometimes I start out having to manually shift, then it works fine.
Also, at times at highway speeds the car drops back into 5th gear. I have to watch the tach for this since I can't often tell it has happened. This is probably due to my driving I would imagine as I change pressure on the accelerator. But it seems overly sensitive to downshifting to 5th.
The two Jaguar dealerships in our general area will no longer perform the ZF 6HP26 JTB00145 adaptations procedure. They tell me that they no longer have the necessary hardware or software to do so (and they really have no interest in working on these old XK8s / XKRs anymore). Some of the local indie shops claim they can do it, but I would investigate them very thoroughly before allowing them to do so....
When was the last time you did an ATF drain-and-fill? If the answer is "never", I would certainly do that ASAP. Many of us have been using Ford's Mercon SP ATF for years. It is essentially ZF's Lifeguard 6 ATF colored red instead of amber, and is significantly less expensive. We have owned my wife's 2006 XK8 since early February 2012. Acquired it at 36,000 miles, and it is now approaching 127,000 miles. I have done four separate ATF drain-and-fills during that timespan, and I had Jaguar Greensboro perform the ZF adaptations procedure in July 2013 and again in April 2016 after my wife complained of intermittent rough shifts. Her ZF continues to perform exactly as designed, and I believe my multiple ATF drain-and-fills are a big reason why....
Since I bought the car in 2014 I have not had the ATF changed. I will definitely schedule it and use the less expensive Ford Mercon SP ATF. I'll hold off on the ZF 6HP26 JTB00145 adaptations procedure for now. But I will call around to the local Jag dealers to see if they can still perform it.
What ATF did you utilize when you did your pan drop and fluid refresh?
most trans fluid change by dropping the pan only get half the fluid drained! Depending on year n trans u might be lucky to have a drain plug in the torque converter then u can drain the rest of the fluid out! I highly recommend the BG trans flush system! It flushes the entire trans n torque converter while adding new fluid! Most modern shops n dealers have this system! I used it in our ford dealership for years with no problems at all!!
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Very interesting!. Clearly, the tinkering you did with new LED brake lights made the Transmission think vehicle was braking. The Transmission Control Module is fed status (Via CAN BUS) regarding the braking condition and will not enable ratio change-up if the brake lights are on. This is irrespective of engine revs and whether you are actually braking or not. So the brake light circuit is key.
As you know, when you depress brake, the pedal switch turns on the brake lights, but also, the system is looking for volt drop to check bulb health. It was this closed circuit that was somehow being fooled and affecting your Transmission operation!
In standard brake light set-up, the system is fail-safe with no affect to gearbox – but there’s one exception to be aware of in future. The brake pedal switch has a little built-in ratchet that can require resetting if the brake pedal has been pulled hard towards the seat, the ratchet will set and the brake lights come on permanently without the pedal being depressed. This situation will also cause the gearbox to not change-up in D-Drive (like your failure mode). So, if same Gearbox fault ever happens again, one check is to see if the brake lights are staying on all the time....
you just saved me my sanity! I was literally about to chase this rabbit down this hole
