[Zaxxon]

722.6 Gurus - New conductor plate needed?

Hello all!

I am a bit stumped with a transmission issue I am having. Trying to give as much background info as I can (sorry, this may be long):

- last Wednesday picked up the car from installing a Remus exhaust. Everything was fine until I stopped at a buddy's shop. Had the car idle in park for maybe 10 minutes. Then shifted into D, but gear would not engage at all. Shifted through the gears, neutral, reverse, park, etc. - nothing. After doing this a few more times, finally car went into gear, I backed out, drove off, all was good.

- Drove the car every day, no issues at all

- Saturday morning I figured I'll do a transmission fluid and filter change, and change the 13-pin plug adapter as well. No problem, done it many times between all my cars with 722.6. Once I had enough fluid in there to start the car and run it through the gears, same thing happened - no gear engaged. Added some more fluid, figured might be the problem, but no, same thing, and it had definitely enough fluid now. Turned the car off, restarted, gears engaged, all was good. Topped the fluid off, all is well, aside from the fact that sometimes it took a second for the starter to start spinning, sometimes it started cranking right away, but then stopped for a moment and cranked again until the engine started. Seemed odd.

- Cleaned up the shop, went on my way home. Car is stuck in 2nd gear! Weird! Oh, duh, I think - I never disconnected the battery before changing the plug. No problem, I'll reset codes in the morning, all will be fine.

- This morning, I read the codes, and see more than I should have. Cleared all codes, went for a drive, and now I am stuck in first gear! Even more weird! Cleared codes again, nope, same thing, stuck in first. Drove to the shop at 25mph (it's not far) to get it on the lift and recheck the plug and so on.

All seemed well. So I dug deeper. Went through the troubleshooting steps, up to the TCM/EGS connectors, all values to spec, no issues, but the codes still come back the moment I start the engine. Same ones as attached. I found when I remove the connector adapter, and connect directly to the pins for the modulator pressure regulating solenoid valve, I have about 5.6Ohm, which would be in spec for 4-8Ohms, but if I push the pins a bit to the left, I essentially get a short (0.5Ohm) between those pins. Odd! Other values don't seem to be affected, and e.g. I get a in-range reading for the temp sensor when the shifter is not in P or N at the plug as well as the TCM/EGS, yet STAR doesn't show me a temperature reading!

Something seems odd. As I mentioned, I can clear the codes, but they come right back after engine start. I no longer have the weird cranking for whatever reason. I checked all wiring everywhere, even cut back the fiberglass insulated loom from the 13pin plug to the firewall and made sure all wired are well. I even put the old connector adapter back, but no difference.

Driving home, I was stuck in second gear again. At least that. No longer 25mph screaming

So, at this point, I am thinking it could only be the conductor plate that gave up the ghost for whatever reason, but before I drain the brand new, expensive fluid to change that, I wanted to check for some opinions here. Any other ideas anyone? I attached the codes that keep coming back.

I really really appreciate any help! I am kind of at my wits end! Thanks already in advance,
--Zax

 

[Ruindr]

Kent Bergsma of Mercedessource has a kit and videos on this. The videos where free a short while on YouTube, and he discussed at length the different issues that leads to changing the conductor plate. Maybe something to check out.

https://mercedessource.com/store/search?keys=722.6

 

[Zaxxon]

Kent Bergsma of Mercedessource has a kit and videos on this. The videos where free a short while on YouTube, and he discussed at length the different issues that leads to changing the conductor plate. Maybe something to check out.

https://mercedessource.com/store/search?keys=722.6

Thanks for the link! I actually did see his troubleshooting video some time ago, and there wasn't really anything in it about these specific codes. At this point, I am just worried that the TCM/EGS might have a sudden issue, and possibly not the conductor plate, however, if that were the case, I'd think I see some CAN related faults rather than actual sensor issues and such. The old connector was bone dry, and no fluid intrusion anywhere, and I really never heard of a random, dry TCM/EGS failure on those transmissions.

The one thing that bugs me quite a bit is that e.g. the lockout/temp sensor pin at the 13pin connector, as well as the connector at the TCM/EGS, shows readings in-range for the temperature and shifter position, yet I get no transmission temp reading in SDS (Star).

 

[lowesguy]

I think Mava here, is the transmission guru .

 

[MAVA]

Apart from having a solenoid problem the Shift switch right on the conductor plate can be your problem too which then allows the temperature to be read.

Have you inspected the TCM for oil contamination? It is located behind the passenger floor carpet. Behind the panel mounted upside down on another bracket. Unplug the connectors, and remove the TCM. Look at the connectors for wetness of oil.. If it is wet, you will need to open the TCM, and clean the TCM. This is how I clean the TCM-Post 15:

http://www.benzworld.org/forums/w21...e-questions-testimony-please.html#post9039089

If you are planing to replace the conductor plate, replace the regulation spring too..

http://www.benzworld.org/forums/w140-s-class/1474350-photo-diy-722-6-conductor-plate.html

Sonnax Regulating Pressure Control Valve Spring - 68942-01

While you in the oily valve body. Check to see how soft the o-rings are on the shift solenoids, and the torque converter solenoids. These o-rings cannot be hard.. The black regulation solenoids need to have a screen filter, and BTW the o-rings are not available separately from Mercedes, so the only way to to get them is to buy a $100 722.6 aftermarket rebuild seal kit.

http://www.benzworld.org/forums/w21...ve-body-rebuilt-transmission.html#post9558858

Hope this helps,

Martin

 

[Zaxxon]

Hi Martin,

This certainly helps. The connector at the transmission as well as the TCM connectors and the TCM are bone dry. Dealt with the oil intrusion on both of my 140s already.

I did already order the Sonnax 68942-01 spring as well as the Sonnax 68942-05K control valve service kit, just because it's an earlier 722.6, and while I am already in there if I change the plate, it seemed to make sense, even at "only" 80k on the clock. My '96 S420 is at 185k and never skipped a transmission-beat aside from the oil intrusion with regular fluid/filter changes and (don't get mad) Redline D4 fluid.

So is it save to say that at this point you would go after the conductor plate, seeing these codes and what I did so far?


Thanks again for all your help - it's much appreciated!
--Zax

 

[MAVA]

Zax,

The pin(s) on the regulation solenoid can have issues. Until you inspect what is down there. It is a guess. The regulation solenoid could exhibit blockage too as many of those early 722.6 valve bodies did not come with screen filters on the the two black solenoids. Maybe the hold down screw got loose on the two regulation solenoids..

I have heard great things on Redline D4 fluid...

Maybe you want to take a peek at the conductor plate/valve body before you buy one?

Martin

 

[Zaxxon]

Zax,

The pin(s) on the regulation solenoid can have issues. Until you inspect what is down there. It is a guess. The regulation solenoid could exhibit blockage too as many of those early 722.6 valve bodies did not come with screen filters on the the two black solenoids. Maybe the hold down screw got loose on the two regulation solenoids..

Hi again! Thanks for the quick reply again! Is that screen available separately, or would you at this point change the solenoids?

One thing I haven't mentioned before is that on this connector replacement the connector was much harder to remove from the transmission/conductor plate side. On the 140s it came out fairly easy after loosening the 7mm bolt. A good tug by hand was all it took. On this one I had to lever slightly with a wedge to finally make it move - maybe I cracked a brittle conductor plate doing so?

I have heard great things on Redline D4 fluid...

Been using it in all my 722.6, and I think it's the D6 I am using in the 722.9. So far never had an issue with any of them. A good friend, an independent Mercedes garage swears by it and uses it exclusively for many years.

Maybe you want to take a peek at the conductor plate/valve body before you buy one?

Martin

I think I want to have a conductor plate here when I take it apart, just so I don't have another delay, and might send it back if not needed. My own shop/garage is just about to be started, so it's always much better when I can finish a job while being on the lift instead of trying for another day where I can get a lift again...

Thanks,
Zax

 

[MAVA]

Zax,

You are welcome.

Until you see what is there. To replace solenoids on a 80kmile car is a waste of $500. Maybe at 170k I will think about it... Screen filters are available from Mercedes. I'd get the two solenoid radiant heat covers too, but only if you replace the conductor plate as they do not fit your current generation of conductor plate..

Loose connectors are usually indication of a past aftermarket connector, but the original connectors had transmission grease on them too, but today no one, or shops put transmission grease on them. They may just wick a little ATF and you are ready to go. May be a little tighter too...

Keep using the fluid you are using. About 40 to 60% of a 722.9 is made up of the exact 722.6 parts. The pump is the same.

Martin

 

[mrboca]

Could it be your shift linkage is slightly out of adjustment ? The TCM complains about a sporadic fault, maybe the magnet operated reed starter lock-out switch is opening and closing due to vibration ?

If the TCM cannot reliably read the ATF temperature, it will substitute with a value from a table, and this can cause some shifting issues.

 

[Zaxxon]

Zax,

You are welcome.

Until you see what is there. To replace solenoids on a 80kmile car is a waste of $500. Maybe at 170k I will think about it... Screen filters are available from Mercedes. I'd get the two solenoid radiant heat covers too, but only if you replace the conductor plate as they do not fit your current generation of conductor plate..

Ok, sounds great...actually just found the filters/screens in EPC - I'll order a couple tomorrow. Do you happen to know if the heat covers will fit a conductor plate that I would purchase now, even if it's not genuine MB, but OEM manufacturer?

Loose connectors are usually indication of a past aftermarket connector, but the original connectors had transmission grease on them too, but today no one, or shops put transmission grease on them. They may just wick a little ATF and you are ready to go. May be a little tighter too...

I am certain that the S420 had an aftermarket connector already, since it was serviced at the shop of the above mentioned friend, and whenever they do a fluid change, they change the connector. On the CL I am not sure, bought it will only 60k and less than great service records. But I definitely had to use a good amount of force to make the connector on the SL move. So much actually that the white lock ring popped off without being in the position where it can...

Keep using the fluid you are using. About 40 to 60% of a 722.9 is made up of the exact 722.6 parts. The pump is the same.

Martin

Interesting! I didn't know that! That transmission scares me a little. I have yet to do a fluid change on it, my friend told me that I can borrow the adapters and pump, etc. needed. But I am pretty sure I stick with the D4/D6, it seems to work well for me. It's by no means cheap either, but if you break it down over the time it spends in that transmission, the price difference to something cheaper is almost negligible. And that's me as a stingy German saying. Hahaha. But some things just aren't worth cutting corners.

Thanks for all your advice,
--Zax

 

[Zaxxon]

Could it be your shift linkage is slightly out of adjustment ? The TCM complains about a sporadic fault, maybe the magnet operated reed starter lock-out switch is opening and closing due to vibration ?

If the TCM cannot reliably read the ATF temperature, it will substitute with a value from a table, and this can cause some shifting issues.

It's certainly a possibility, however, until last week I never had any kind of shifting issues, but who knows! I know for a fact that there is a bit of slop in the linkage because of deteriorated linkage bushings, which I already have on order as well. I'll have a look at that!

Thanks for the pointer - much appreciated!

--Zax

 

[MAVA]

You are welcome...

Ok, sounds great...actually just found the filters/screens in EPC - I'll order a couple tomorrow. Do you happen to know if the heat covers will fit a conductor plate that I would purchase now, even if it's not genuine MB, but OEM manufacturer?

I'm Very sure all the clone conductor plates will fit the covers as I do not run into old conductor plates. I have no clue who OEM is for the conductor, and the only people I would trust when saying OEM is AutohauzAZ as I know the heater tee on a W140 is made by Rein which is the identical Mercedes Tee, and Autohauz sell that tee. All the other folks claiming OEM are "Royal Fakes". Now Clone conductor plates. It can be any one. I used a Beck/Arnley connector a few times, and no problem. No URO or Dorman for me on those. Maybe other can chime in. A member on the W140 forum posted a Conductor plate/filter/ connector for $60/$70 on ebay if it works that may be an option.. A buddy of mine just spent $300 or so on all lifetime warranty suspension parts for his W140 from eBay, I spent around 2k in parts with a two year warranty, so what gives?



I am certain that the S420 had an aftermarket connector already, since it was serviced at the shop of the above mentioned friend, and whenever they do a fluid change, they change the connector. On the CL I am not sure, bought it will only 60k and less than great service records. But I definitely had to use a good amount of force to make the connector on the SL move. So much actually that the white lock ring popped off without being in the position where it can...



Interesting! I didn't know that! That transmission scares me a little. I have yet to do a fluid change on it, my friend told me that I can borrow the adapters and pump, etc. needed. But I am pretty sure I stick with the D4/D6, it seems to work well for me. It's by no means cheap either, but if you break it down over the time it spends in that transmission, the price difference to something cheaper is almost negligible. And that's me as a stingy German saying. Hahaha. But some things just aren't worth cutting corners.

Just Change the fluid every 30k Miles, and every 60k Miles pull the valve body down to clean the bottoms of the solenoids, and like every few years or so do a documented adaption value test for clutch pack to see what are the fill times( to find the change of wear). Lastly, they are easy to diy like a 722.6. If you ever get a speed sensor error, requires a conductor plate change. The Chinese make the actual speed sensor fix for $50 or so instead of buying a $1800 conductor plate...

Thanks for all your advice,
--Zax

 

[Zaxxon]

Thanks again everyone that chimed in for your help and advice. I love this forum. There is so much knowledge here!

Here is my plan of attack, probably happening at the end of the week. I ordered the following (remember, fluid/filter/connector just changed this past weekend):

- New Conductor Plate
- 2 Solenoid Screens
- Solenoid Heat Shields
- Shift Linkage Bushings
- Sonnax 68942-05K Overlap Control Valve Sleeve Kit
- Sonnax Regulating Pressure Control Valve Spring - 68942-01
- New, large oil catch pan to save the new D4. Luckily I pretty much surgically cleaned the pan while I had it off the car a few days ago, and will clean/blow dry the pan again thoroughly before draining and removal to limit the chance of contaminating the fluid.

I will setup a very clean area to work in/on and seal the drained oil for the work time.

Any other advice anyone wants to throw my way, maybe from someone that has done this kind of service? Even though I didn't have any kind of shifting/performance problems from the transmission at all, I figured it makes sense to upgrade to the Sonnax parts while I am in there and add the solenoid screens and heat shields...

Thanks again, you guys are the best,
--Zax

 

[Zaxxon]

Just to bring this thread to a close - everything is working perfectly, and trouble found! As I had expected, I pretty much did it to myself and "broke" the conductor plate. As I had mentioned, I've did these connector replacements on 722.6 quite a few times and never had an issue like on this car. This connector was stuck. And not just a little. It was in there like someone used JB Weld on it. In the process of Me leverying/twisting, I was a bit too forceful, and the connector did not appreciate that at all. I actually must have twisted it quite a bit as you can see in the picture. This caused a few traces to short out, and that was the problem. In all reality, I could have probably twisted the connector back into the correct position and left it at that, but at 80k it was probably a good thing to change the conductor plate anyways.

And while I had everything apart, I put the upgraded Sonnax spring into the valve body, as well as the upgraded, o-ringed overlap valve slides from Sonnax. I tried to also retrofit the screens under the two soleniods, but for some reason it felt like the solenoids don't bottom out with them in there and don't provide solid connection, so I took them back out.

I happened to swing by my friend's shop yesterday, and he had a 722.6 on the bench that had just ingested some needle bearings and failed catastrophically, but I snatched the two radiant heat shields the newer transmission have and retrofitted them to the newer style conductor plate after thoroughly cleaning.

One thing I realized is that one of the landings for one of the solenoids has some casting issues from the original cast it seems. It's not pretty, but also shouldn't cause any problems if it doesn't get any worse, since at this spot that void is just fine with how the o-rings are. Just wondering how this passed MB quality control! Guess eventually I snatch a good valve body if I come across one and change it some time down the road, but it really doesn't look like it's at risk of getting worse.

Put everything back together, added fluid, ran SDS and all is well! Took the car for a spin, and it's shifting like new. Perfect. The shifts are even a bit more crisp and firm now, just feeling very solid and precise.

Thanks to everyone that chimed in, and especially Martin with his great knowledge about these transmissions! So much appreciated!!!

--Zax

 

[Ruindr]

I'm truly impressed. Great work! Surely not for the average DIY'er!

 

[Zaxxon]

I'm truly impressed. Great work! Surely not for the average DIY'er!

You know, to be totally honest, with the right care and preparation, and definitely a clean work surface, it's really not that bad of a job. I mean, I've been working on cars since I was maybe 12 years old, but this job isn't terribly complicated or so. Cleanliness is important, and so is to stick with the correct bolt torques. Speaking to a MB tech, they actually use new bolts whenever they R&R a valve body.

So thank you, but I do think someone with a good set of tools and some wrenching experience can definitely do it. Just go slow, work diligently and double/triple check each step.

--Zax

 

[Mlucas500]

Apart from having a solenoid problem the Shift switch right on the conductor plate can be your problem too which then allows the temperature to be read.

Have you inspected the TCM for oil contamination? It is located behind the passenger floor carpet. Behind the panel mounted upside down on another bracket. Unplug the connectors, and remove the TCM. Look at the connectors for wetness of oil.. If it is wet, you will need to open the TCM, and clean the TCM. This is how I clean the TCM-Post 15:

High Mileage Questions/Testimony please.

If you are planing to replace the conductor plate, replace the regulation spring too..

Photo DIY- 722.6 Conductor Plate and Pressure Regulator...

Sonnax Regulating Pressure Control Valve Spring - 68942-01

While you in the oily valve body. Check to see how soft the o-rings are on the shift solenoids, and the torque converter solenoids. These o-rings cannot be hard.. The black regulation solenoids need to have a screen filter, and BTW the o-rings are not available separately from Mercedes, so the only way to to get them is to buy a $100 722.6 aftermarket rebuild seal kit.

E320 rebuilt valve body or rebuilt transmission?

Hope this helps,

Martin

Martin, would you say a non oem conductor plate could cause issues with the 722.6 transmission? I installed a dorman in mine, and I keep circling back to the same codes...even after installing a new plate and 13 pin connector

 

[sushipaste]

Martin, would you say a non oem conductor plate could cause issues with the 722.6 transmission? I installed a dorman in mine, and I keep circling back to the same codes...even after installing a new plate and 13 pin connector

Why would you ever put aftermarket shit parts into a Mercedes transmission? Especially the conductor plate??? Its an electrical item for a critical system and its a pain in the ass job so why risk having to do the job again? I'm guessing the electrical connector and fluid was aftermarket and non approved too...

Here's all the correct stuff you need: Mercedes 722.6 Conductor Plate Transmission Service Kit - OE Supplier 7226CSK

Here's the correct dipstick as well that you MUST have: Mercedes Automatic Transmission Dipstick - Febi 140589152100

Aftermarket conductor plates never ever work properly. Once the job is done correctly clear the codes with STAR diagnostic then report back.

 

[Mlucas500]

Why would you ever put aftermarket shit parts into a Mercedes transmission? Especially the conductor plate??? Its an electrical item for a critical system and its a pain in the ass job so why risk having to do the job again? I'm guessing the electrical connector and fluid was aftermarket and non approved too...

Here's all the correct stuff you need: Mercedes 722.6 Conductor Plate Transmission Service Kit - OE Supplier 7226CSK

Here's the correct dipstick as well that you MUST have: Mercedes Automatic Transmission Dipstick - Febi 140589152100

Aftermarket conductor plates never ever work properly. Once the job is done correctly clear the codes with STAR diagnostic then report back.

Thank you sushi plate, I guess I tried to save a few bucks and I bit me in the ass. I’ll give this a try !