This is a continuation of my previous post https://www.jaguarforums.com/forum/x...faults-159221/ related to problems with my ECM/TCM which has now morphed/transformed/relapsed to different codes after all codes have disappeared for about 7 days.



My XK8 will now start normally, but within 2 minutes will light the dash Amber warning light together with "GEARBOX FAULT“ spelled out loud. Codes pulled are

• P1722
• P1730
• P1797

 

I'm locked into "Limp-home" mode, viz. locked into either 4th/5th gear with revs limited to 1,600rpm. If you've stopped at a red light on a slope, its gonna take quite a while to get up to speed whilst holding up traffic behind, as you've only got help from your torque converter rather than gear ratios.

The fault codes P1722, P1730, P1797 can be found in the DTC Summaries, 5 HP 24 Transmission Control System - 1997 MY courtesy Jagrepair.com.

The question is, what should I be fixing ??? PLEASE HELP!

 

In your OTHER thread you seemed to end it saying it has been running well for 5 days??????? So now this is a new thread on that older one and it is acting up again?
I have to assume the by the ECM pics that it has an burned up part on it, needs fixed?

 

brgjag:

Yes, this is a new thread. The blown capacitor and transistor in the ECM has been replaced and faults all cured, but that lasted for only 10 days. Now its acting up again with DTC P1722, P1730, and P1797, basically kicking in within 2 minutes of engine start, showing GEARBOX FAULT with the Amber warning light. That means I'm in "Limp home mode", locking the tranny in 4th/5th gear and restricting engine RPM to under 2,000.

HELP!!!

 

The XK8 starts everytime with no warning lights. Within 2 minutes of driving in “D”, it may rev up to 3,500 rpm and up shift only when you let your foot off the accelerator, and then on the next shift you may experience a slight jolt, and then the Amber warning light will come on and car go into "Limp home mode". The following pic is an extract from the Transmission Control Module DTC Summaries MY1997~1999, explaining the DTC codes P1722 & P1730 I'm pulling.



Under the "Possible Causes" column, it states the problem may be due to problem with the "Input/Output Speed Sensor".

Can someone enlighten me with what exactly are "Input/Output Speed Sensors", and how can I determine they are faulty or working???

 

I knew I was saving this for someone, someday:

https://www.jaguarforums.com/forum/x...rmation-78132/

 

It's been almost a month, and I've been driving her around with the Amber warning light lit and GEARBOX FAULT dash warning coming on within 2 minutes of driving, sometimes accompanied by a BIG THUMP from the ZF5HP24, depending on how I moderate the throttle, but sometimes it lit up without me noticing.

The ZF5HP24 speed sensors I ordered took awhile to arrive from the US, and after they arrived I had to wait for my indie to give me a spot to put her into his workshop. The speed sensors were finally replaced today, but NO LUCK, the same problem remains.

Let me describe the situation in detail. On startup, putting her in Drive, I get a very gentle surge forward in about 3 seconds, and then no more traction. I have to then put her back in neutral and then Drive to get further traction forward. After repeating the sequence for a couple of times, I'm finally able to get some forward speed. But sometimes it may over-rev and not moving forward correspondingly... so I have to ease off. And then, the tranny may sometimes give out a BIG THUMP, and sometimes it may be quite smooth, but the Amber warning light and GEARBOX FAULT warning would ultimately come on, and I'd be locked into "Limp home mode" in 5th gear, with engine revs limited to 1,500rpm below 50kmph, meaning I would not be able to pull up any incline even though very small from a standstill, but REVERSE is fine, allowing me to take an escape by backtracking downhill if I'm stuck on an uphill. When stopped at a red light on level ground, I would have to floor the accelerator to start moving again, maxing out @ 1,500rpm and with the torque converter growling since I'm in 5th gear. After attaining 45kmph, she can accelerate to 80kmph with almost unnoticeable torque converter noise. She can go uphill at ease even doing 120kmph.

The DTC codes pulled are still the same P1722, P1730 & P1797.

P1722's heading is "Transmission stall speed failure". Does it mean something is wrong with the torque converter?

P1730 says "Gear control malfunction - 2nd, 3rd or 4th" which makes sense because before the Amber came on, I don't seem to be upshifting like normal.

P1797 says "CAN ECM token message missing". My ECM was fixed like 2 months ago, but it can be bad again. Also can my TCM be bad? Also can a bad Throttle Body be causing this?

I really need your expert opinion(s) to help me resolve this lingering problem. TIA.

 

Have you contacted ZF Technical Support to discuss your issues? If not, I suggest you do so. Go to their web page and locate the contact information for the Asia Pacific region, then phone them and ask for their automotive transmission tech support department....

 

Thank you Jon89 so much for your suggestion. Upon searching in zf.com, there is indeed a ZF Company in Hong Kong. I will call them up first thing tomorrow morning (Monday) to seek their assistance. Hong Kong is such an insignificant market for cars or industrial products that we generally do not expect there would be a direct company contact based in the city, but apparently not so for ZF. I do hope they can directly give me a solution, failing which they can at least channel my problem to their worldwide technical service team, but not refer me back to the local Jaguar/Landrover dealership who simply lack the technical competence to deal with my problem.

ZF Services Hong Kong Ltd.
Nos. 29-35 Sha Tsui Road
2/F, Technology Plaza
Tsuen Wan, New Territories
Hong Kong
Hong Kong
Phone +852 2615 9353
Fax +852 2615 9689
E-mailzfhk@zf.com
Websitewww.zf.com/cn

 

I called up ZF Services Hong Kong this morning. They were unable to help as they do not deal with transmissions for passenger cars. So I called ZF in the UK in the afternoon.

ZF Services UK Ltd
Eldon Way, Crick Industrial Estate
Crick
NN6 7SL
Northamptonshire
Great Britain
Phone +44 333 240 1123
Fax +44 (0) 8442 570 666
E-mail info.zf-services-uk@zf.com
Website Technologies made by ZF - ZF Friedrichshafen AG

I spoke to a Product Support Technician. He listened to my symptom description, then asked for the codes I scanned, and looked up their own DTC fault descriptions, and told me the most probable cause is the A-clutch aka A-drum failure because I was unable to engage 1st, 2nd, 3rd, or 4th.

I will be calling ZF in North America right now just to double-check the fault before making the finally decision. Stay tuned. Thanks for watching.

 

ZF Services, LLC
777 Hickory Hill Drive
Vernon Hills , Illinois 60061
USA
Phone +1 847 478 6868
Fax +1 847 478 6843
Website Technologies made by ZF - ZF Friedrichshafen AG

The ZF Regional Service Manager there was most helpful and also concluded that my A-Clutch (aka the infamous A-drum) has failed.

I've already located a second-hand ZF 5HP24 locally and will try swapping it in.

Gents, wish me luck. Are there any specific procedures I should be undertaking?

Thanks for watching.

 

Just be aware that if you rebuild your own transmission with a new A drum it will be the modified strengthened one - the used transmission you are considering will have the old ,prone to failure, design.

 

Agreed. The vast majority of folks with the 5HP24 unit decide to install the new-and-improved A-drum. And it will cost you considerably less than swapping out the entire transmission assembly....

 

Thank you so much batroute and Jon89 for your most valuable comments.

Now that I have a clear picture of what components have failed in my transmission, my next move is to obtain quotes from local transmission specialists (there are not that many competent specialists available locally in a small place like Hong Kong) as to how much it would cost to replace the A-drum and install the improved pressure regulating valve in the valve body. I was told by my indie mechanic that local transmission specialist would tend to replace ALL replaceable parts when they rebuild a transmission in order to avoid having to tearing it down a second time if the fault is not cleared, and that would jack up the total cost for the rebuild considerably, way above installing a secondhand tranny.

I can also request the yard who would sell me the secondhand transmission (the whole package includes removing my busted tranny and reinstalling the used tranny) to fit the improved pressure regulating valve in the secondhand tranny.

I will keep you guys posted on my progress. Thanks for watching.

 

I'm in the process of swapping my busted 5HP24 for a secondhand one. I'm considering also having the infamous pressure regulating valve replaced with an upgraded valve during the swap.

My question is do I just pull and replace it with the new pressure regulating valve without any worry for the wear and tear cause by the old valve in the valve body? Should I also install a new valve body just to be safe?

 

I'm not a transmission expert but I would be more concerned about the A drum. If was my transmission I would replace the A drum and the pressure valve. I believe the valve body should be OK unless it had problems before. The valve body if it does cause problems later can be replaced without removing the transmission. But if the A drum fails it will have to be removed.

 

I agree with BobRoy - the A drum would worry me more than the pressure valve. It (the A drum) is definitely the weak point in these transmissions.

 

Thank you so much RobRoy and batroute for your advice to replace the A-drum as well as pressure relief valve while doing a secondhand transmission swap. But due to the lack of properly ZF-trained service personnel available locally in Hong Kong, I tend to try my luck with the motto: "If it ain't broke, don't try to fix it".

After all, fully reconditioned 5HP24's are readily available at very reasonable prices from the U.S. and the U.K. if I'm so unlucky as to encounter another "Gearbox Fault" with the secondhand transmission, I'll just have to bite the bullet. Therefore I'll leave it to the Almighty Lord to plan my destiny...

Wish me the best of luck. Cheers!

 

There is some talk that the A drum is a symptom of a problem with the main pressure regulator valve rather than a problem as of itself.

ZF has strengthened the A drum, but has also issued a modified valve. See this thread on the X308 forum: https://www.jaguarforums.com/forum/x...69/#post658838

I agree that much of the evidence is anecdotal, but I have read enough to convince me to commit to preventative maintenance replacement while my car has relatively low mileage.

I am by no means a transmission expert, but there is enough information on this forum to give me the confidence to take on the job.

Just my $0.02

Mike

 

You don't need to be ZF trained to replace the A drum. I'm a Drywall contractor and not a brain surgeon and I have done it successfully 3 times. A year ago I had never been inside a transmission before but with the process being laid out with photos in this forum I was able to get it done. With the transmission out of the car I can change the drum in about an hour. I believe that you have changed the tensioners in your Jag. If you can do that you can change the drum.

If you don't want to do the drum thats fine, but you don't know the condition of the drum in this used transmission. It could be in good condition or it might be starting to fail. It might last another 100,000 miles or it might go out next week.

Best of luck on whatever you decide.