ZF 5HP24 Problems - help needed!
 

This is the THIRD time I have the transmission (ZF 5HP24) out of my 02’ E53 X5 4.4 and it is still not working correctly. I’m at a point of pure frustration dealing with the trans and I’m not really sure where to go from here.

The first time I pulled the trans I replaced the torque converter and replaced the pressure regulator valve with the upgraded one from TransGo (to address issues with torque converter lock-up codes as well as harsh shifting and going into fail-safe). After getting the trans back in was still having problems now with a new series of codes. When selecting a forward gear (reverse functioned normally) there was a slight delay and then it "clunks" into gear. If by some luck it doesn't immediately go into trans safe mode by then it will shift harshly with the engine freewheeling/revving up before hunting for the next gear. The codes I was getting were P0750 and P0751 and seem to indicate an issue with "shift solenoid A." After doing a lot of research I became convinced it was an issue with the A-Clutch drum.

The second time I pulled the trans I found that the O-ring seal between the A and B clutch drum was split which seemed to explain all the remaining symptoms I was having. I got the trans back in and went back for a test drive and noticed that it was no longer banging into gear when I engaged drive and was very hopeful that it was finally fixed. However, before I even got out of the driveway it went into fail-safe and I was absolutely devastated. It was showing the P0751 “Shift solenoid A stuck off” code again so I crawled back under the car to recheck the electrical connections and trans fluid level. Before I set off again, I reset trans adaptations with INPA hoping it may be a TCM learning issue. This time I actually got to witness the transmission shift and was astonished to see that it was behaving absolutely normally. The shifts were smooth and quick with no free wheeling or hunting for gears. I was really hopeful but after 2 miles of my test drive the dreaded fail-safe signaled itself across the dash even though it was otherwise behaving normally.

I now have the trans out a THIRD time and have dug a bit deeper by disassembly the A and B clutch assemblies. I checked all their various seals expecting another leak, but everything looks pristine and undamaged. I used INPA to pull up the error history and noticed a low voltage error. Since the car has been sitting for so long my battery no longer holds a charge for more than a day or two without use and I usually have to jump start it before each test drive. I’m beginning to suspect that the issue may be a bad battery, but I would think when it's running it would have more than sufficient voltage to not effect function of the trans.

I’m really at a loss here and don’t want to have to put the trans back in this car again until I’m certain I fixed the problem. Unfortunately, I’m out of ideas and I’m hoping that the collective knowledge of the forum may help me in this fiasco.

Currently I feel doomed to be spending the rest of my life just pulling the trans and putting it back in again…

Man, what a battle.
I think you are on the right track with the battery.
Low voltage will absolutely affect the shifting strategy.
You've checked the sealing sleeves as well I'm sure.
If not I would replace them but I think your issues are voltage related.

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Forgot to mention, you can check the clutch packs for leakage with compressed air with the valve body removed.

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Thanks so much for your quick reply.

I did air test the a/b drum, but I've not air checked through the valve body.

Do you know of any way to confirm if the battery could be causing this without putting the transmission back in?

Thanks again.

Does your car have the IVM? Integrated Voltage Module.

maybe transfer case is going bad with the front drive shaft mine (mine clunked too going into gear) did that before my transfer case went just and idea

Like you I had a problem with a slipping transmission, now 8 or 9 years back. I am curious about your approach to the problem. Why did you change the torque converter? I.e., what made you believe it was the source of the problem? Weres there any symptoms or diagnosis once you removed the torque converter that indicated a problem?

On the second attempt, did you change all the seals in the trans when you had it out? I had mine out at 93k miles and the seals were generally brittle and nasty. Something else maybe faulty if you didn't refresh them all. Did you clean out the valve body at the time?

Finally. did you check that solenoid A is functioning properly? IIRC it can accessed with trans in the car.

Although there are a lot of stories of bad batteries causing issues, your fault code is quite specific. Like you, I am inclined to think that once the car is running it should provide enough juice to run the systems, but a new battery wouldn't hurt.

Can you explain how you did that in the software

I actually have not checked the sealing sleeves. Would anyone be able to tell me where they're located and how to check them?



Is it possible for these sleeves to cause my symptoms?

I believe either within the "coding" or "error" menu within INPA there is an option to "reset transmission adaptations."


In my opinion, this is a more full proof way of doing it over the gas pedal method.