Hello, sorry if this is poorly formatted or not in the right thread, i own a 2011 e550 4matic with 79k miles, and just recently it’s needed to be towed to my home because the car can no longer get out of park, but it can start. I’ve read up on here quite a bit and I’m assuming my problem is the ism, and I guess what I’m asking everyone is how would I start to diagnose and mend this problem? I know it’s something I DEFINITELY cannot do myself, but I’m honestly just confused about who to send this to or where to have this diagnosed at, and if anyone knows anything i may be missing or should check before I find a repair service that’d be a plus too, thank you all for your time
I have since followed the steps, and have still not been able to get any gear changes. The car does not show that it is in park until I put the ignition into position 2, but it’s still red highlighted and says that it’s not in park. Sometimes it will return white and show its in park but the moment I try to shift it doesn’t respond and goes red again, I have started purchasing a icarsoft diagnostic scanner hoping to find out what’s wrong, any input on steps, pricing, places or people to go to, how to remove the ism on a w212, all these things would be tremendously helpful for anyone who sees this thread, thanks
I have since followed the steps, and have still not been able to get any gear changes. The car does not show that it is in park until I put the ignition into position 2, but it’s still red highlighted and says that it’s not in park. Sometimes it will return white and show its in park but the moment I try to shift it doesn’t respond and goes red again, I have started purchasing a icarsoft diagnostic scanner hoping to find out what’s wrong, any input on steps, pricing, places or people to go to, how to remove the ism on a w212, all these things would be tremendously helpful for anyone who sees this thread, thanks
Confirm your code with your new scanner that your ISM (<PRND> actuator) is bad, not the DSM selector reporting through SCM and not wiring
A new ISM module needs to activated online with Xentry.
Plan B: you can get your unit refurbed so no coding necessary for a fraction of the cost.
I used to think this module couldn't be opened... Actually it can get worked out with a heat gun to soften the sealant. I don't exactly know what causes
Confirm your code with your new scanner that your ISM (<PRND> actuator) is bad, not the DSM selector reporting through SCM and not wiring
A new ISM module needs to activated online with Xentry.
Plan B: you can get your unit refurbed so no coding necessary for a fraction of the cost.
I used to think this module couldn't be opened... Actually it can get worked out with a heat gun to soften the sealant. I don't exactly know what causes ISM internal failure YT Video
Off to the dealer you go, it's an anti theft part and nobody else can sell you a new one or program it. Don't waste time with a repair service, they have a high failure rate.
I have since followed the steps, and have still not been able to get any gear changes. The car does not show that it is in park until I put the ignition into position 2, but it’s still red highlighted and says that it’s not in park. Sometimes it will return white and show its in park but the moment I try to shift it doesn’t respond and goes red again, I have started purchasing a icarsoft diagnostic scanner hoping to find out what’s wrong, any input on steps, pricing, places or people to go to, how to remove the ism on a w212, all these things would be tremendously helpful for anyone who sees this thread, thanks
I have since put an icarsoft scanner on the car to try and get an idea of my issues, below are the dtc codes from the ism, I couldn’t find any other codes from any of the systems, I’m assuming I’ll need a new ism (I’ll be going to Mercedes dealership to have it replaced) but I wanted to post these and run it by anyone with knowledge; do these codes point to a new unit? Is there anything else I’ll need to replace or I should check before I swap the ism? I apologize if it’s not a lot of info to run with
Yep, that makes sense.
This unit is said to use a belt... I dont know exactly what is the weak link as it is glued shut.
This module provide wealth to a cotage industry fixing MB modules.🤘
Im just gonna leave it in the hands of the professionals, my only issue now is just trying to find transportation for the 34 mile drive to the dealership, pending it won’t get out of park lol
Im just gonna leave it in the hands of the professionals, my only issue now is just trying to find transportation for the 34 mile drive to the dealership, pending it won’t get out of park lol
the main point of this thread for me was to kind of get an idea of my failure and how to tackle it, since then I think I’m well footed as far as how to go about it now and got my price point on the replacement ($1000 roughly, quoted from dealer), I could probably save a lot of money and time going with a repair but it’s far too intimidating for me lmao, just wanted to thank you for your help, you may have just helped saved my ****ty w212
I found this video showing the internals of ISM and DSM ...
This video is a great find, excellent presentation ! Thank you @up_too_late
Besides what we all heard, I will add this:
> the water damage looks like it comes from connector leaky seals (RTV it!) perhaps helped by the shaft itself (Silicone grease it!).
> Lastly it looks like a solderless connected board. So after a while contacts simply go flaky under repeated surge currents.
It may also be that PCB was "desoldered" but unlikely knowing love for solderless....
Board uses a conformal lacker a rare occurrence in this line of products. Good to see.
PCB connection pins...
Video confirms...
security needs to be coded to match the car. Fixing your own matched module saves that trouble.
> Failed units:
Almost nothing to loose then open your unit to:
This video is a great find, excellent presentation ! Thank you @up_too_late
Besides what we all heard, I will add this:
> the water damage looks like it comes from connector leaky seals (RTV it!) perhaps helped by the shaft itself (Silicone grease it!).
> Lastly it looks like a solderless connected board.
pic.
Video confirms...
security needs to be coded to match the car. Fixing your own matched module saves that trouble.
@CaliBenzDriver , you are referring to how the card connects to the mechanical components
Ouch!!.. .. That means, not only water intrusion, but vibrations on the board <-> mechanical components can trigger all kind of gremlins.
I am afraid my car may need some checking. A few weeks ago, it hesitated to shift when parking, noticed the Xentry error, deleted it and all good until brother call me last Sunday telling me my car did not want to shift to reverse. Told him to turn the car off, lock the doors (double click on the keyfob), try it again and the car shifted again.
It seems a Xentry-centered weekend is coming up soon, fingers crossed
Juan, your bro's experience with goofy no-shifts pretty much confirms "solderless" pins are in use....
solderless PCB connection 🤪
> No Go Caro:
DSM ghosting may help create the "no-crank" conditions when security is breached by broken handhake.
> Combo of moisture + solderless:
As soon as a little moisture gets inside, the solderless pin oxidation is accelerated to crash that module.
Xentry errors tell tale sign of what's cooking for those of us who like connect dots to understand evidences.
> Sweet disruptions:
I don't know what CAN network DSM is on, I can guess CAN-C with VIP Tranny-ECU-Pump. I can guarantee that when poor PCB connections create high retransmit, that CAN bandwidth gets pacted (extra slow) with traffic jams.
> Practically:
you can sense that condition when said bus or module gets slooow scanner response. Until packets timeout, no codes get registered.
This a super insightful reading doc to set our records straight with VIP modules interactions when bad solderless steering module messes up tranny...
"The Intelligent Servo Module(ISM) receives connection from the Controller Area Network(CAN) which enables it share information with other units such as the:
Central Gateway Unit
Transmission Control Unit
Electronic Ignition Switch (EIS)
Steering Column Module
Instrument Cluster!!
Electronic Stability Program(ESP)
Mercedes Intelligent Servo Module comes with huge cost in terms of replacement and a bit moderate in-terms of repairs.
.....
SYMPTOMS OF FAULTY ISM:
Vehicle hardly start.
Vehicle’s gear wont shift.
Revs at high rpm.
Cluster light goes off.
Vehicle wont crank due to loss of communication from the Transmission Control Module.
Error data from actuator motor in the component A80 of the Intelligent Servo Module(ISM)
Ain't that fascinating?!?
Remember how I found that fixing my solderless steering column + EIS modules made my car drive planted on the road and tranny shift smooth like a CVT. It drives like a different car.
It's in the thread where I fixed clunky "convenient entry" column.
Having this knowledge may force me to pull my working DSM for performance enhancement.
Prime example of how we overcome issues jointly as a group, not individuals.
👏
Check f88 @ rear SAM in trunk if fine, ISM replacement.
@konigstiger can you please do us the favor of posting the WIS procedure to drop/install this module. I am wondering if any sort of spline alignment is used to guide position.
It seems like only 2 bolts hang it plus a coupling shaft adapter is used between module/tranny
.. That means, not only water intrusion, but vibrations on the board <-> mechanical components can trigger all kind of gremlins. 
