Diagnosis and Parts for 722.6/W5A580 Transmission
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722.6/W5A580
Diagnosis and Parts for 722.6/W5A580 Transmission
Hi folks, thanks for letting me join. I've been reading a lot of posts on this forum, and other MB forums. I understand if this thread gets deleted, but I'm trying to take a measured approach to my concern and not shotgun parts. I apologize if there is a better forum this thread belongs in. If it isn't deleted, I'd ask any moderator to please move my thread to a more suitable forum/subforum.
My 2012 model year vehicle has the W5A580(NAG1), which crosses to the later 722.6. I understand that nobody here can provide a diagnosis for me, but I'd like to narrow down the problematic part based on behavior. I'm of the impression that it's likely related to the conductor plate, TCC solenoid, or the TCC regulator control valve spring.
To clarify, I have no codes, no wicking of ATF up through the harness into the TCM, no particular drivability issues outside of behavior of the TCC, in specific circumstances. The fluid I have changed since I've owned this vehicle appears to have been in fair condition and I have drained and filled the sump several times during my 1.5 years of ownership.
Regarding the issue, my home is next to a relatively steep hill, and after a short drive on flat roadway, I have to go up that hill in 2nd gear at about 15-20 MPH. You can feel the torque converter locking and unlocking repeatedly, every couple of seconds, which can be manipulated by throttle input. If you balance the throttle input and maintain a constant speed up the hill, this does not occur. I'm not sure if it's related, but torque converter release upon a downshift at highway speeds, while on a grade (up a hill) can be somewhat firm or fast, but I wouldn't describe it as harsh.
Based on this information, can you help point me in the right direction? I haven't done an ohm test on the solenoids through the conductor plate pins yet, but may try that as well. Again, I know this is a bit unorthodox, but I've been lurking these forums so long, I almost feel as though I belong!
My 2012 model year vehicle has the W5A580(NAG1), which crosses to the later 722.6. I understand that nobody here can provide a diagnosis for me, but I'd like to narrow down the problematic part based on behavior. I'm of the impression that it's likely related to the conductor plate, TCC solenoid, or the TCC regulator control valve spring.
To clarify, I have no codes, no wicking of ATF up through the harness into the TCM, no particular drivability issues outside of behavior of the TCC, in specific circumstances. The fluid I have changed since I've owned this vehicle appears to have been in fair condition and I have drained and filled the sump several times during my 1.5 years of ownership.
Regarding the issue, my home is next to a relatively steep hill, and after a short drive on flat roadway, I have to go up that hill in 2nd gear at about 15-20 MPH. You can feel the torque converter locking and unlocking repeatedly, every couple of seconds, which can be manipulated by throttle input. If you balance the throttle input and maintain a constant speed up the hill, this does not occur. I'm not sure if it's related, but torque converter release upon a downshift at highway speeds, while on a grade (up a hill) can be somewhat firm or fast, but I wouldn't describe it as harsh.
Based on this information, can you help point me in the right direction? I haven't done an ohm test on the solenoids through the conductor plate pins yet, but may try that as well. Again, I know this is a bit unorthodox, but I've been lurking these forums so long, I almost feel as though I belong!
Thread Starter
Newbie
Joined: Aug 2022
Posts: 2
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722.6/W5A580
Thank you, I appreciate it! I found a couple diagnostic troubleshooting guides and it appears I can ohm out the TCC solenoid through the pins on the conductor plate. Does anyone know if this has to be done under certain conditions (idling, in gear, etc) or are we simply checking resistance in the circuit itself? I can get a replacement solenoid and new o-ring easily enough. It's tempting to do the conductor plate "while I'm in there" but I'm not sure if it's worth making this harder than it needs to be.
