722.9 Woes
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Joined: Jun 2019
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W220 S320 CDI
722.9 Woes
Hello all. I'm having some issues with the 722.9 in my 2005 320 CDI. A few weeks ago as I was coming home, I discovered that the car was stuck in third. As I pulled into my drive, I lost all drive. To cut a story short, I discovered that one of the fittings to the cooler had worked loose, and the car had dumped A LOT of its ATF over about a mile (the refill suggests about 4 litres). I was incredibly lucky that it happened as I was returning home.
Over the next week, I used the overflow method to refill the ATF, and after a little babying and line repair, the car was back to operating normally. Fingers crossed no major damage had been done.
Until this week however, when the car has a couple of times gone into limp mode, and some of the shifts have been a little slow, or *weird*. Last night it did this and wouldn't go into reverse until I restarted the car. This is happening every half hour to hour of driving (with normal shifting for 99% of the time), and a restart of the car solves the issue completely. Hooking up to iCarsoft, I'm getting a transmission error in the ECU, and the TCU seems to think it's not getting a signal from one of the sensors I believe to be on the conductor plate.
The question is this; is it likely that the tranny being very low on fluid has caused an issue with the conductor plate, or am I looking at something mechanical that is upsetting a sensor? I'm hoping the former, and research suggests my symptoms are typical of conductor plate issues, but I can't see how low ATF could have caused this?
Over the next week, I used the overflow method to refill the ATF, and after a little babying and line repair, the car was back to operating normally. Fingers crossed no major damage had been done.
Until this week however, when the car has a couple of times gone into limp mode, and some of the shifts have been a little slow, or *weird*. Last night it did this and wouldn't go into reverse until I restarted the car. This is happening every half hour to hour of driving (with normal shifting for 99% of the time), and a restart of the car solves the issue completely. Hooking up to iCarsoft, I'm getting a transmission error in the ECU, and the TCU seems to think it's not getting a signal from one of the sensors I believe to be on the conductor plate.
The question is this; is it likely that the tranny being very low on fluid has caused an issue with the conductor plate, or am I looking at something mechanical that is upsetting a sensor? I'm hoping the former, and research suggests my symptoms are typical of conductor plate issues, but I can't see how low ATF could have caused this?
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W220 S320 CDI
Just a quick update. The code culprit is y3/8n3, the output speed sensor on the conductor plate. Doesn't look like this one usually causes trouble which is a bit of a concern. P2203 says that its 'internal electrical check' has failed, but I struggle to see how this relates to the fluid issue.
Out Of Control!!
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From: unbegrenzt
2017 GLE350 4MATIC
The photos of conductor plates I have seen for the 722.9 tell me there is oil interacting with the solenoids. So lack of oil as you experienced could possibly create a malfunction of failure on the conductor plate. I would not rule out a component failure on the conductor plate. Also be super, super, duper sure you have a full fill of fluid.
Does the W220 have an aux battery? I think the 7G transmission shift function partially relies on the aux battery. I would replace it if you have one.
Does the W220 have an aux battery? I think the 7G transmission shift function partially relies on the aux battery. I would replace it if you have one.
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s500 2006
I had a similar code. it pointed to one of the solenoids. My symptoms were rough shifting. Thinking I just needed a fluid change, I did just that. After the fluid change, The car would shift but the tranny would not get into gear. I removed the conductor plate at least 3 times, thinking I mis-installed it, or was low on fluid. I researched which solenoid the code referred to. then I replaced that solenoid. Still got the code. I ended up replacing the TCU. Since my unit was VGS1 so I had to replace the TCU along with valve body. I sourced a used valve body and got a brand new TCU from the dealer. I had someone program the TCU to the car and the car shifts and works brand new.
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W220 S320 CDI
An update on this. I changed the fluid again to make absolutely sure that it's at the right level, and it is. Car is shifting perfectly except, still once every half hour or so of driving, it'll go wrong, and P2203 is triggered, which iCarsoft points to as an electrical fault with speed sensor 3. With a friend in the car, we've verified that the sensor dropping to 0rpm while moving is what seems to trigger the code, at which point it freezes at 8000rpm. Certainly sounds like a sensor issue now, though it's still odd that few other people have an issue with this particular one. I'm now going to see about having the sensor replaced. One question I have though is that I'm not totally sure which sensor I'm looking for. y3/6n3 is what iCarsoft is telling me, but it seems from diagrams that the sensor is actually called y3/8n3 on the 722.9. Does anyone know enough to clarify? Thanks!
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W220 S320 CDI
What might STAR be able to tell me that iCarsoft can't? I can already see the data that I need, and iCarsoft can read all of the codes. The only real discrepancy I've got is y3/8n3 vs y3/6n3.
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s500 2006
I beleive there are 2 types of selenoids in the car. black and green one. one for each direction of flow. It's hard to say if the solenoids failed, or the ribbon connectors to the solenoids, or one of the many passages through the valve body to the solenoid is clogged.
I went from rough shifting to NOT GOING INTO GEAR at all when I took my valve body down to replace the suspected solenoid.
You are welcome to try to replace it, but the risk is your car would be disabled. for these trannies, i believe you should check to see what version valve body and TCM you have. if you have version 2 or 3, then just replace the TCM. if you have version 1, you may have to replace both TCM and valve body. and it needs a real SDS to program. NOT the china ones.
I went from rough shifting to NOT GOING INTO GEAR at all when I took my valve body down to replace the suspected solenoid.
You are welcome to try to replace it, but the risk is your car would be disabled. for these trannies, i believe you should check to see what version valve body and TCM you have. if you have version 2 or 3, then just replace the TCM. if you have version 1, you may have to replace both TCM and valve body. and it needs a real SDS to program. NOT the china ones.
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Out Of Control!!
Joined: Sep 2018
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From: unbegrenzt
2017 GLE350 4MATIC
Last edited by chassis; Aug 4, 2020 at 11:29 PM.
