Hi everyone,

So I have a daily driver and my jag sits for decent periods of time. One day I got in it and for whatever reason it has problems shifting out of low gears. Now, there was a small transmission leak which could have finally caught up with it and now causing problems. The weird part is when I switch to manual shifting, it shifts just fine. Also DSC message began to pop up for no reason (car driving stable), so I have to turn DSC off to drive normally. I've read somewhere that ABS sensor issues could cause transmission shifting problems and faulty DSC messages. I'll take it to a mechanic here in a bit, but just wanted to see if anyone has any ideas? To me, it's weird that in manual it shifts normal, so could it still be actual transmission issues?

 

Yas459,

Yeah, you’re right in all your suspicions. I’ve only got hands on experience with the ZF5HP24 unit on earlier cars, but everything you pointed to are relatively easy fixes.

Do you have a good DTC OBD reader to get codes? Post them here.

Hope you caught this problem early as rebuilding the tranny is a BIG expensive job.

If the ATF fluid is low level, old fluid and/or dirty ATF normally causes the auto ZF gearbox to “stutter. ” Solenoids in the ZF unit uses fluid pressure to change gear. Manual selection in the J Gate selector avoids this, so car seems to drive fine.

How big was your ATF leak? Was it topped up when fixed? Maybe time to consider fluid and filter change. This is DIY able at home for experienced “wrenches.”

Also if the wheel speed sensors are dirty/bad this normally causes ABS and DSC problems. The Transmission Control Module uses this speed data to choose what gear. Cleaning the wheel sensors is a very easy home DIY able job. Also the wires to the front sensors are known to stretch/snap (probably due to steering geometry).

Good luck and let us know what the mechanic says. If your mechanic can read the TCM DTC codes, post them here.

 

Thank you for the reply.

I did take off the front end ABS sensors and cleaned them, but everything remained the same. The wires to the sensors seem fine. It's a little bit more work to take the rear ones off (will have to take off the tire), do you think it's worth a shot before I take it over to the mechanic? It's weird to me that if the sensors were faulting out, the ABS light isn't coming on. I do not have a DTC scanner, but can take it over to autozone and get a print out from them. Will try that just to see if there are any clues in that.

 

Their tool will only show codes in the PCM, not any other (such as ABS).

 

So quick update.. I had to take it to a couple places before could even figure out what's wrong. So apparently there's a small plastic bridge that holds the valve body in place, which broke. That applied extra pressure on a couple solenoids in the trasmission which caused them to fail, intermittently, so far. Now they told me the "zf transmission solenoid kit" itself isn't that expensive, however apparently everytime you replace solenoids in a Jag, the whole transmission has to be reprogrammed to accomodate those new components. Since it's a bit of an older model, the programming tool is difficult to find and the one they did find, the place wants to charge around $1500 just to do that. So in total, with labor, just to replace those solenoids and reprogram the transmission is around $4,000. Even though the parts themselves are only around $500. Since I'm trying to actually get rid of this car, the repair shop told me it might not even be worth doing and to just sell as is.

My question is has anyone heard of this and is that true about the reprogramming part, seems a bit off to me. Unless it's some Jaguar only quirk? Anyone has any suggestions?

 

Yas459,

How did the garage confirm their findings? I presume they had the SDD OBD2 reader software to access the TCM module to read the transmission DTCs.

If you are changing the valve body bits, then the garage is probably right in that you need to reset the TCM and do an adaptation run out in the car. More capable home DIY "shade tree" mechanics have this software to hand on an old laptop & "mongoose" OBD2 cable, at home, to re-programme any of the modules on the car. I'm considering buying it, but just haven't had the need yet.

You will be in a tricky situation - selling an old car with a automatic gearbox problem. That will put off a lot of buyers and they will argue to lower the purchase price drastically due to the high cost of the repair.

Good luck on which ever way forward you choose.

 

First, you need to have the codes read with a proper Jaguar Land Rover scanner. Without that, you are flying blind. Worst case, buy one, should be < $200. I have a Foxwell unit, others have iCarSoft. Check eBay/Amazon.

Next, if the car is sitting, the health of the battery becomes suspect. Weak batteries cause dropping voltage at startup, and control module can get into a funk when not properly powered. ABS/TRAC is usually the first one to fail.

Next, double check your brake switch. There is an adjustment on the "trigger". If it is too loose, the car "thinks" you have your foot on the brake and will not upshift unless you switch to "5" and then back to "D" for every shift. Easy to check as the brake lights should be on too.

Next would be a "complete" trans service. This is a new pan/filter, new bolts, new connector sleeve, new bridge and tube seals. This is fairly generic work as that transmission has been used in several make/models. Some/most of us have switched to the lower priced Mercon SP instead of the ZF Lifeguard 6. It matters double as you are not going to be able to flush it all in one go. You will have to redo the drain/refill a bit later to increase the ratio of new fluid. If you are going to do this on your own, read up as the fill procedure is temperature based. You will need to pull the valve body to get to the bridge seal, but this is all done from under the car, no need to pull the transmission off. Expect a few hundred dollars for this, this is not a hard job for a shop.

The decision to be made is of course to change the solenoid valves or not. They are several hundred $ for a set, but easy to replace once the valve body is on hand. Trouble is, if going that far, maybe consider a "new" complete valve body. The scanner codes will help for this decision. If you discover a broken bridge seal, then maybe take a chance and forget about the solenoids for now. FWIW, ericson industries has great ZF tech support for these transmission and may help you with a pro opinion. Many have called and been able to talk to real transmission pros with TONS of experience.

Once all of that is done, you need to do a couple of software procedure. One is to update the trans software (reflash). A dealer can do it for a nominal diagnostics fee (say, 1.5 hour labor). It requires the SDD software on a laptop. This may not be necessary if you get a valve body from a reputable source as I believe it comes with a "new" control module already updated. Obviously, you will have to turn yours in as a core. The other procedure is a "reset of the adaptations". This is done to make the trans software "learn" from the new fluid and valves and make your car shift as smoothly as possible. Some hand held scanners can do this, but the vanilla software is SDD again. This consists of driving the car around with mild accelerations through the gears under the direction of the software.

Of course there are other possibilities. Check the wheel bearings and reluctor rings as they can "lie" about the true speed of the car. There would be codes for this (incorrect speed ratio, etc.).

So, this is the lay of the land, so to speak. Best of luck, keep us posted.

 

Have your shifter cable adjustment checked first.

Gus
JagRepair.com - Jaguar Repair Information Resource

 

This is incredible sir, thank you very much. Unfortunately I am no car guru myself, so a lot of this is definitely out of range for me. But at least I have a direction to point someone as far as step by step elimination to get to the root of the problem. Will consult with a couple people to try and find the best bodies for the job.

The most annoying part is I had a very knowledgeable Jaguar (and others) mechanic that I've used for years for this car. Unfortunately, I only knew his business number and he either sold his garage or moved, with no trace, sometime in the past year. So I've been trying my best to track him down with no luck. Will sure to keep this updated when I, hopefully, get some progress.

 

Ok, will give that a go.

 

Also I think I should mention that when I took it to a trans shop. The guy was driving it around trying to get a feel for the issue, however couldn't get it to fail for like 2 days of driving. It was shifting just fine even in automatic for him (never for me whenever I've driven it). I think that's also why he might have thought the solenoids were failing intermittently.

Could that narrow any of your hypothesis down some?

 

I had this same problem on my car and it was the shifter cable adjustment. See my post.

Link. JagRepair.com - Jaguar Repair Information Resource

Gus
JagRepair.com - Jaguar Repair Information Resource

 

Will do sir, thank you very much. Is it something I can take a look at myself or do I need a lift and/or full set of tools?

 

You will need to get under the car and remove the center console to make the adjustments. No special tools just do not over torque the nuts or bolts. Just look at the TSB that on that page.

Gus
JagRepair.com - Jaguar Repair Information Resource

 

tl;dr; CODES, CODES, CODES!

Yes, you need to locate a shop with proper diagnostics tools! Does not have to be Jaguar, but a shop you can walk away from with a list of trouble codes. And no, the generic tools from the parts store will not do. Post the codes here, and we can have a look (no promises). Resist the urge to reset the codes as it may hide issues for the next tech to look into. Or do reset the codes, reproduce the problem and read the codes again for a possibly shorter list. Unfortunately, there is no time stamp on these codes, so it is hard to tell how long they have been there.