722.6 Speed sensor/conductor plate

[V6Matty]

+1 for what Star said, i know mine won't go into 5th untill it's going 42, my display it the same as yours, shows the number up till 4 then just D.

 

[panason1c]

OK, so now no limp mode! Yaaaaay!

BUT It will only shift up to 4th...

When I first start the car, with the gearbox now in 'S' mode, I can manually shift 1-2, 2-3, 3-4. When I try to go into 5 it just displays "D" and stays in 4th.

:arrow: Anyone got any ideas????

Are you certain it's sticking in 4th and not going into 5th?, what are your revs showing at when you are doing 70?

 

[bed_sat]

It's doing 4,300 ish revs at 70. The display shows 4th. When I move the stick right to go to 5th the display changes to 'D' and the revs stay the same.

It then won't let me change down by pushing the stick left (I know it only locks the gearbox to that as the highest gear), even if I slow down before pushing the stick.

The replacement TCU came out of a 2004 E220 CDI that had been in a front ender and has all the same numbers on it.

 

[bed_sat]

Sorry for not keeping you informed recently, been so busy hardly had time to fart!

Hopefully going to be able to get it on the machine later today to reset the adaptive data and test for and clear any codes.

I'ill post the outcome later!

 

[bed_sat]

OK, so here's an update.

It's not 5th it doesn't change into, it's 4th.

On initial startup the shift lever works fine, and if I push left until '3' is selected in the display the car runs, changes up/down and drives perfectly.

The second I push right to go to '4' or 'D' it goes into soft limp mode, and stays in 3rd. Won't change back down, and it feels like it's slipping.

Switch ignition off/on, everything fine (no slipping) until it once again tries to go into 4th.

cleared adaptive data and codes and got exactly the same result.

Checked for codes after, and get just the one - "P2502 - Gear Implausible or Transmission Slipping"

Bugger! :cry:

Not sure what to try next.......!

 

[vazh]

it has to be one of the solenoid valves on the valve body - had the same problem once and it was sorted this way but cant remember which valve it was.

 

[bed_sat]

it has to be one of the solenoid valves on the valve body - had the same problem once and it was sorted this way but cant remember which valve it was.

That would make sense, and something I've been mulling over myself - there is a single solenoid that operates the 3-4 shift and it might be that it's faulty or I didn't seat it properly when I refitted it after the conductor plate change - or it could be a sticking valve in the valvebody.....

Think I'm going to have to drop the pan again and have a good look.

It's just a complete pain in the backside as I'll have to do it on ramps in the drive this time....! :roll:

 

[bed_sat]

it has to be one of the solenoid valves on the valve body - had the same problem once and it was sorted this way but cant remember which valve it was.

It's the Y3/6y4 solenoid that controls the 3-4 shift.

If you look at the last page here:-

http://www.sf.nexedge.com.my/140/etm/webetm/140/systeminfo/docs/gf27.10_00g_04g_07g_08g_09g.html

It shows the valves labelled 28c, 29c, 30c and 31c as those operating the 3-4 shift. They're all on one end of the valvebody next to the gear selector valve.

It's these I intend to take out clean up and have a good look at; as well as removing and replacing the solenoid itself

 

[bed_sat]

Well, yesterday I took valvebody out and changed the 3-4 solenoid, cleaned all the valves up and put them back. Refilled with ATF.

Result - still exactly the same.

Now thinking it could be the torque converter, so might as well get a replacement gearbox at the same time and do the whole lot.

It may well still be something simple, but by the time I've thrown more parts and money at it I might as well have changed the whole box/TC.

 

[knowlep]

722.6 Gearbox Conductor Plate Speed Sensor Fix

ML270 Cdi 2001.
Fault = Occasionally gearbox would clunk at slow speed and go into limp mode i.e. engine lacked power when trying to pull away from standstill, gearbox seemed stuck in one gear unwilling to change (could be any gear just the one it was in when it failed), Tiptronic would not work, cruise would not work, limiter just beeped 5 beeps and would not work, no warning lights on dash.
Stop and re-start engine and fault would disappear only to strike again at any time from immediately to days or weeks later but got progressively more frequent to more than once a day.
Gearbox level was correct, gearbox electric plug had been renewed a couple of years earlier showing no sign of wicking out and up the loom, box also had a part fluid change with filter and gasket at that time.

Solution that worked:
Replaced the conductor plate with one from "One Stop Gearbox Shop" (they quoted genuine OEM and it seemed to be just that) with fluid change, filter and gasket and new electric plug (again). £138 without fluid as I used Genuine Mercedes ATF.
I noticed that one of the speed sensors on the old plate (which are both magnetic) had a build up of a type of grey paste (that's the best I can describe it) which didn't look like metal or anything bad just a small accumulation over the 15 years of gearbox use. It sat about 5mm thick on top of the one speed sensor and I wondered if simply clearing this off and refitting the who lot might cure it as it could possibly be interfering with the signal.....but we'll never know as I fitted the new plate.
The fix worked perfectly and I didn't "Have" to get any codes cleared but as I knew someone with a code reader he cleared them off for me just for my peace of mind.
Whole job is quite simple for a good DIY mechanic but be careful when inserting valve block back into gearbox that the sliding shaft lines up with its pin.

I've included links to the old plate which I dissected as I'm like that....wanted to see what was inside.

https://drive.google.com/open?id=0B21WAfUncNWoUC1QRDJXTzFmTXc
https://drive.google.com/open?id=0B21WAfUncNWoZlU4Mk5lSTBRY3M
https://drive.google.com/open?id=0B21WAfUncNWoYzhIRnNtWF92V0U
https://drive.google.com/open?id=0B21WAfUncNWocEQ3cGNDbVBXaHc
https://drive.google.com/open?id=0B21WAfUncNWoV1l0T3ZWa3c5YkE
https://drive.google.com/open?id=0B21WAfUncNWoZFpxWVVnQXhGaEk
https://drive.google.com/open?id=0B21WAfUncNWoal9DbVFUeVdVSUk

 

[umblecumbuz]

..... I've included links to the old plate which I dissected as I'm like that....wanted to see what was inside.

https://drive.google.com/open?id=0B21WAfUncNWoUC1QRDJXTzFmTXc
https://drive.google.com/open?id=0B21WAfUncNWoZlU4Mk5lSTBRY3M
https://drive.google.com/open?id=0B21WAfUncNWoYzhIRnNtWF92V0U
https://drive.google.com/open?id=0B21WAfUncNWocEQ3cGNDbVBXaHc
https://drive.google.com/open?id=0B21WAfUncNWoV1l0T3ZWa3c5YkE
https://drive.google.com/open?id=0B21WAfUncNWoZFpxWVVnQXhGaEk
https://drive.google.com/open?id=0B21WAfUncNWoal9DbVFUeVdVSUk

Know your pain!
Up top somewhere is a sticky showing the disaster I had when I tried to remove the pilot bush. The 7mm captive bolt refused to come out, although it turned easily enough. The brass threaded bush embedded in the conductor plate was simply turning with it, so I had to cut it out once I'd got the sump off and the valve body out. Messy business.

Replaced conductor plate, pilot bush, etc and all has been well since.

Umble.

 

[mercedes13156]

If you're talking about taking the valve body and solenoids out again, why don't you find someone with an iCarSoft 980 and check the live data in the gearbox before you start taking it to bits again. There's enough live data on switches, solenoids and sensors to let you know what's broken, so that you can go straight to it.

 

[Michael Calvert]

If you're talking about taking the valve body and solenoids out again, why don't you find someone with an iCarSoft 980 and check the live data in the gearbox before you start taking it to bits again. There's enough live data on switches, solenoids and sensors to let you know what's broken, so that you can go straight to it.

Have u got information as to what they should read