It's kinda funny, I was just referencing one of your threads from 2012 last night hoping to find some answers for my issues.


Regarding your questions: The trans it out of an 02' X5 4.4 with about 145K miles



The reason I changed my torque converter (TC) was because of progressively worsening systems over the period of about a year. It started with a significant drop in fuel economy, then noticing there was no lock-up occurring in high gear, harsh 2-1 gear downshifts, then the car chattering (like going over a rumble strip) when leaving from a start and finally the trans going into fail-safe mode with a TC failure code. Fluid changes helped in the short term but the symptoms worsened over time. I researched this quite a bit before I dug into the trans and found that the pressure regulator commonly fails in this unit and can take out an internal seal in the TC.


The second time I pulled the trans I replaced only a few seals (A/B clutch drum, and 4 of the fiber rings) as well as a faulty axial bearing that was missing a roller (luckily I found the roller in the clutch drum so it's not hiding somewhere in the trans doing unspeakable damage). I rechecked my installation of the pressure regulator valve and everything appeared to be clean and in nice shape.



I only removed the half of the valve body with the pressure regulator. I have not touched the one with the solenoids. I did use INPA to perform a manual function test on the solenoids and they all passed. Is there a way for me to function test the valve body with the trans out of the car? It's currently sitting in my garage and I have no intention on reinstalling it until I'm quite certain I found the issue.


I agree with you about the battery. This car developed a slow voltage drain over years over ownership and I have yet to find why the car won't go to "sleep." Regardless, it's been known to kill a new battery within a year and there have been MANY times that I've had to jump start this car in the past. No matter how dead the battery has been, once the car is running I've never had transmission issues so I don't know why it would start now.


Thanks for your questions and insights!

It's entirely possible that the now very tired battery is causing the trans fail safe. Have you monitored the alternator output voltage while it's running?

BTW, resetting the trans adaptation with the throttle is a myth....

Yeah, I kinda assumed that matting the throttle to the floor for 30 sec. didn't really do a thing.


My only concern about the battery theory is that I've jumped started that car numerous times before with a dead battery and never had any issues with the trans function. What do you think could be causing it to act differently now? Is there a way to be certain that battery is the cause?



My understanding is that it needs 9 volts to function without issue with the trans but who really knows. I truly hope that it is just the battery because that means I could just reinstall it tomorrow and be back on the road again.

At the time I did mine, the TC puked a whole bunch of metal shavings in to the transmission. So, I cleaned everything and fully replaced all seals as well as the clutch disks.

I am not an expert on these transmissions at all and I can't see an obvious reason for your issues (RRPhill is the guru but I don't know if he stills contributes?). If it were my car and the trans out for third time, I'd go whole hog and completely refresh it including the valve body. But that is just me.....

Yes, there is. I often test hydraulic solenoids as a heavy duty mechanic. There's a way.
Resistance check - usually 15 to 30 ohms
Shuttle check - apply voltage and release it. I take a screwdriver touching the solenoid body and put to my ear. If I can hear it click in and out, it's working.

But the 'professional' way to test it applying a voltage while hydraulic pressure is flowing in the circuit. You need a special transmission valve body dyno that only special rebuild shops have.

I did use INPA to perform the solenoid function test while the car was running and everything passed. I could actually hear the solenoids working during the test. Do you think that is sufficient to rule out the solenoids or do you recommend also doing the resistance and shuttle check?

Yeah, it's really unfortunate that I don't see RRPhill posting anymore, he seemed like the guru for all things ZF trans.


Unfortunately, this rebuild is on a tight budget and I'm not able to throw parts at the car unless it's deemed necessary. I'm trying to be as methodical as possible.


I wish there was a way to override this fail-safe. The trans functions absolutely normally when it's not stuck in that mode. It's almost too sensitive for it's own good.



ZF trans be like: low voltage = fail safe, dirty fluid = fail safe, oh no, a squirrel is on the road, better throw it in fail-safe just to be sure :rofl:

The three MV solenoids are simply ‘on-off’ solenoids that operate at 12V and click open at around 220mA and close at around 80mA.

https://i260.photobucket.com/albums/...psz8iwuz4o.jpg

The five EDS solenoids operate at 5V and, because they’re proportional, it’s not really possible to test them without a hydraulic source. A resistance check will tell you if the windings are intact, but it won’t tell you if the solenoid is working.

I have all my valve body assemblies tested on a Hydra-Test machine after I’ve rebuilt them.

https://i260.photobucket.com/albums/...psavtutfra.jpg

https://youtu.be/bFgB_OW9_PA

You must have similar test places in the US? Some places can just test the solenoids, even if they can’t test the whole valve body assembly. The most popular test equipment in the US for car transmissions is manufactured by SuperFlow, who market a range of test machines under the Axiline name, so you could maybe find a place which uses their equipment? Generally the solenoids on the 5HP24 are pretty reliable, in contrast to those used in the 6HP26, which are the opposite.

https://i260.photobucket.com/albums/...psxeigdxha.jpg

https://i260.photobucket.com/albums/...pseq5gxgwq.jpg

Phil

Hi RRphil,


Thanks so much for joining this thread. Your wealth of knowledge concerning these transmissions is unparalleled!


I used INPA to perform of function test of these solenoids with the trans in the car and the engine running. Is this a valid test? Given the COVID situation, unfortunately most shops in my area are closed or not taking new customers right now :(



Also, INPA shows 4 error codes that are unfortunately in German. I've tried referencing the codes but I'm not sure if what I found is accurate.



I have not done anything with the solenoids thus far. Being that the consistent fault code is P0751 (Shift Solenoid A Stuck Off) do you know which of the solenoid(s) this corresponds with?


Have you ever encountered this trans going in fail-safe while in Park before? Given that the trans seems to function absolutely normally when not in fail-safe I'm curious what you think may be causing this.


I have video of the car driving and going into fail safe if that is useful. With the trans out right now I also can provide pictures of the parts themselves.


Thanks again!

Can you post the error codes? Sometimes they are pretty cryptic but sometimes they lead you right to the source. I read German but not very good at deciphering the more cryptic messages, either way, let's see what you have. (By the way, FCP Euro seems to be ope and they are not too far from you in CT.)