Instructional: Cleaning the TCM - Transmission Control Module
Thread Starter
Senior Member
Joined: Dec 2001
Posts: 494
Likes: 13
From: Amber waves of grain.
2000 CLK430 Cabriolet
Instructional: Cleaning the TCM - Transmission Control Module
Re.: CLK430 Cabriolet, Chassis# W208, Trans#722.623, Engine #113.943
Instructional: Cleaning the TCM - Transmission Control Module
Where to find TCM.
How to remove TCM.
How to remove circuit board from cover.
Then squirt away with electrical cleaner on circuit board and connectors.
When re-inserting the board into the cover, it neatly and simply snaps together.
Instructional: Cleaning the TCM - Transmission Control Module
Where to find TCM.
How to remove TCM.
How to remove circuit board from cover.
Then squirt away with electrical cleaner on circuit board and connectors.
When re-inserting the board into the cover, it neatly and simply snaps together.
Last edited by Pancho; Jun 16, 2012 at 01:03 PM.
Thread Starter
Senior Member
Joined: Dec 2001
Posts: 494
Likes: 13
From: Amber waves of grain.
2000 CLK430 Cabriolet
Symptoms, earlier this week:
Engine reved, then jumped into gear hard.
Downshifting stopped working.
Pull away from a stop in 4th gear.
This went on for about 24 Hrs., then CEL came one.
Hooked up my multiplexer and got code P0715.
Had replaced the A/T Adapter 2 Yrs. ago, and did not clean TCM.
So, pulled and cleaned TCM a couple of days ago.
Had a slight slick feeling on cable and connectors,
but nothing visible. Nothing visible on the inside of TCM either.
Cleaned it with electronic cleaner anyway.
Reinstalled TCM, cleared P0715 code, and drove it for a couple of days,
and same symptoms reoccurred.
So, I am left with only one option:
Yesterday, ordered conductor plate; pan gasket, filter, and copper washer.
Looks like I'm be taking an A/T fluid bath and visiting the valve body next weekend.
Wish I had a lift.
Engine reved, then jumped into gear hard.
Downshifting stopped working.
Pull away from a stop in 4th gear.
This went on for about 24 Hrs., then CEL came one.
Hooked up my multiplexer and got code P0715.
Had replaced the A/T Adapter 2 Yrs. ago, and did not clean TCM.
So, pulled and cleaned TCM a couple of days ago.
Had a slight slick feeling on cable and connectors,
but nothing visible. Nothing visible on the inside of TCM either.
Cleaned it with electronic cleaner anyway.
Reinstalled TCM, cleared P0715 code, and drove it for a couple of days,
and same symptoms reoccurred.
So, I am left with only one option:
Yesterday, ordered conductor plate; pan gasket, filter, and copper washer.
Looks like I'm be taking an A/T fluid bath and visiting the valve body next weekend.
Wish I had a lift.
Newbie
Joined: Nov 2018
Posts: 3
Likes: 0
W203 C240
Hi There,
I'm having a similar issue with my C240 W203 (2002 build).
Symtoms:
Gear indicator often wouldn't show anything, just blank. When this happen, the car would only be moving without shifting gear (is this the "limp" mode?)
Sometimes it would not play up and it'll just drive like a normal car.
Sometimes,, when the gear indicator doesn't show anything when the position is at P, i can change it to N and then turn off the ignition, and then turn on at N position, it would show up and drive normal.
I've tried changing TCM. the first one was bathed in transmission fluid when I opened it up.
After changing the TCM, it drove well for the first 1 hour, and then similar symptoms appeared again.
I've changed the conductor plate. no difference
I've checked all solenoids in the transmission.. all normal reading.
I've battled with this transmission issue for more than a year and half now.. honestly getting really tired with Merc.
Thanks beforehand,
Cheers
I'm having a similar issue with my C240 W203 (2002 build).
Symtoms:
Gear indicator often wouldn't show anything, just blank. When this happen, the car would only be moving without shifting gear (is this the "limp" mode?)
Sometimes it would not play up and it'll just drive like a normal car.
Sometimes,, when the gear indicator doesn't show anything when the position is at P, i can change it to N and then turn off the ignition, and then turn on at N position, it would show up and drive normal.
I've tried changing TCM. the first one was bathed in transmission fluid when I opened it up.
After changing the TCM, it drove well for the first 1 hour, and then similar symptoms appeared again.
I've changed the conductor plate. no difference
I've checked all solenoids in the transmission.. all normal reading.
I've battled with this transmission issue for more than a year and half now.. honestly getting really tired with Merc.
Thanks beforehand,
Cheers
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MBWorld Fanatic!
Joined: Nov 2001
Posts: 1,258
Likes: 209
From: Boston North Shore
2001 CLK320 Cabrio
Following the MB updated transmission service recommend would have avoided all of the the above (see link below).
https://mbworld.org/forums/clk-class...ml#post7609533
Note to astha2:
Limp mode occurs when the transmission detects a fault and to protect itself from futher damage, will only operate in 2nd and reverse gears. The transmission system also has a shift module, located inside the center console, which may be faulty or the TCU is not recognizing it's signals. Also, depending on the module and/or fault code, after replacing the part, the diagnostic fault codes need to be cleared as well as checking that the version coding is correct, before the system will operate normally.
https://mbworld.org/forums/clk-class...ml#post7609533
Note to astha2:
Limp mode occurs when the transmission detects a fault and to protect itself from futher damage, will only operate in 2nd and reverse gears. The transmission system also has a shift module, located inside the center console, which may be faulty or the TCU is not recognizing it's signals. Also, depending on the module and/or fault code, after replacing the part, the diagnostic fault codes need to be cleared as well as checking that the version coding is correct, before the system will operate normally.
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Newbie
Joined: Nov 2018
Posts: 3
Likes: 0
W203 C240
Following the MB updated transmission service recommend would have avoided all of the the above (see link below).
https://mbworld.org/forums/clk-class...ml#post7609533
Note to astha2:
Limp mode occurs when the transmission detects a fault and to protect itself from futher damage, will only operate in 2nd and reverse gears. The transmission system also has a shift module, located inside the center console, which may be faulty or the TCU is not recognizing it's signals. Also, depending on the module and/or fault code, after replacing the part, the diagnostic fault codes need to be cleared as well as checking that the version coding is correct, before the system will operate normally.
https://mbworld.org/forums/clk-class...ml#post7609533
Note to astha2:
Limp mode occurs when the transmission detects a fault and to protect itself from futher damage, will only operate in 2nd and reverse gears. The transmission system also has a shift module, located inside the center console, which may be faulty or the TCU is not recognizing it's signals. Also, depending on the module and/or fault code, after replacing the part, the diagnostic fault codes need to be cleared as well as checking that the version coding is correct, before the system will operate normally.
Thanks. I'll give this a try. Again, thanks. ^_^
Newbie
Joined: Apr 2019
Posts: 3
Likes: 0
C230 Kompressor 2002
Hi astha2 where you able to figure out what was the problem with the transmission? I'm dealing right now with the exact same symptoms as you, and I've changed shifter, and I'm in the process of cleaning my TCM, although it looks fairly clean, the cables are filled with oil. I'm driving fine and suddenly, limp mode starts and can't go pass D-N to R-P, only if I turn of the car. It's being an annoying issue to solve 
Senior Member
Joined: Nov 2017
Posts: 321
Likes: 17
2000 ML55 AMG 2001 CLK55 AMG coupe 2002 CLK55 AMG Cabriolet 2025 BMW M2 6MT
Hi astha2 where you able to figure out what was the problem with the transmission? I'm dealing right now with the exact same symptoms as you, and I've changed shifter, and I'm in the process of cleaning my TCM, although it looks fairly clean, the cables are filled with oil. I'm driving fine and suddenly, limp mode starts and can't go pass D-N to R-P, only if I turn of the car. It's being an annoying issue to solve
have the EXACT same issue.. ever figure it out? Thanks!
Newbie
Joined: Mar 2026
Posts: 4
Likes: 0
R107, R129, A208
To add some options here
i was suffering limp mode and yes, I had oil among the cables and a small spill in the TCM, not affecting electronics
it would have confused most of us into being one of the solenoids or the o-ring at the 722.6 electronics but that was not the case.
in my case, it was the shifter.
inside the shifter there is a n electronic module, that moves along with the lever, and based on copper mechanical contacts, tells the ECM exactly what gear you are in.
the contacts lose pressure with time and the contact is not clean.
I cleaned the copper pists and approached the contact giving a little bit of extra tension to the copper foils .
That totally solved the issue
My synthoms were more than limp mode. Sometimes I struggled to engage D or R
Likewise, the gear light was not very precise and sometimes was not lit
i was suffering limp mode and yes, I had oil among the cables and a small spill in the TCM, not affecting electronics
it would have confused most of us into being one of the solenoids or the o-ring at the 722.6 electronics but that was not the case.
in my case, it was the shifter.
inside the shifter there is a n electronic module, that moves along with the lever, and based on copper mechanical contacts, tells the ECM exactly what gear you are in.
the contacts lose pressure with time and the contact is not clean.
I cleaned the copper pists and approached the contact giving a little bit of extra tension to the copper foils .
That totally solved the issue
My synthoms were more than limp mode. Sometimes I struggled to engage D or R
Likewise, the gear light was not very precise and sometimes was not lit
