i was trying to send you a private message, but your inbox is too full and wouldn’t let me.

 

I’ve been trying to actuate the ISM with multiple tests and I getting communication errors :/

 

Now things are getting interesting. I ran the scan while the engine was on and the misfire returned. Ignore the faults for the engine cooling fan as I had it unplugged so it wouldn’t drain the battery when the vehicle was turned off. I also may have forgot to plug in some thing in the passenger foot well so ignore that as well.

They’re definitely seems to be something wrong with the CAN system in regards to communication communications with the ISM.

Below is the latest scan and screen captures of different faults… enjoy

 

The scanner report provides you with a comprehensive view of what's rolled up like a snowball.

One thing led to another starting with the battery "drain by parking" that ended by locking up your ISM.

It can be overwhelming to grasp where to begin.
Action --> reaction = PRND now stuck!


> ROOT CAUSE...
How to catch the root of this ?
(here we can ignore ESP fault)

Fixing the main upsets should allow normal processing to resume like a good car.

Let's make progress in these three devices:
3:CGW < 2:ISM < 1:FAN
.../Cont'd/...

 

So,I need to start by inspecting the central Gateway it’s wiring specifically? I was looking this morning and it’s located behind the glove box correct in the foot area?

 

Nooo... hands off the wiring for now!

CGW is built on the same circuit board as the F-SAM power manager ("fuse box").
Something is overwhelming the Main CAN Gateway into SLOW processing - A rather commun occurence with limited visibility.

+++++
Let's make progress in these three devices:
3:CGW < 2:ISM < 1:FAN

> CGW:
read the details of what is causing active keepawake fault


> ISM:
Seems maxed out and safety locked.
Try to issue command back to "Normal" operating

maxed out... locked for now


rescue back to normal operation


> FAN:
Got to troubleshoot what condition is causing it not to stop.
Guessing ECU is positively commanding it to run
poke at ECU to read the A/C pressure.


missing two more faults....


EZS now good!

good deal on the surgery

 

OK, lol I won’t touch the wiring

I tried putting the transmission back into normal mode last night, but I kept getting communication errors.I’m recharging the battery again just to be sure then I’ll hook it back up and see what happens when I perform a scan.

And the two remaining false, were the fan not being detected because I unplugged it to keep my battery from draining overnight.

I’m not sure, but I think they keepawake. Fault might be due to the scanner being plugged in for a prolonged period of time.

I purchased two of these and they arrived yesterday. They say hello on them and there’s a Mercedes badge that’s kind of scratched off which is kind of odd. Should I install them just to see what happens?




I’ll give you breast of any updates. Thanks again!

 

Usually I don't bank on random luck... replacing working genuine parts with questionable after market.
You don't want to introduce extra variables in your already busy mix of faults
else you land with a situation that hardly make any sense.

Disconnecting Main batt without AUX triggers ISM safety protection that ends up in a hard lock up. Hopefuly ISM can be unlocked without replacement.

> Battery service order...
Disconnect: Aux then Main
Reconnect: Main then Aux (within 20secs.)
Lastly clear live faults.

 

Curious, the latest scan after making sure the batteries are at full charge…

 

this is your $2000 Off victory 👏



open issues....



A/C has a sensor issue



OUCH... the steering column gear selector stolk !!

Your EZS + CGW + ISM are now working.
Glad for you.


> Next Top Targets...
Your car is getting ready to become driveable again:

1. SCM direct select
2. FAN needs troubleshooting
3. ECU misfires?

Basically SCM stolk commands ISM selector on high-speed CAN-C across the VIP CGW gateway module. ECU depends on PRND status to crank in "P".

 

How might I go about tackling the steering column module?

 

SCM is one of the module featuring the amazin' solderless pin you've meet in the EZS.

This module share similar fare with optical sensor and pins ... needs "clean" table to open up. It is a bit on the delicate fragile side.

> You can decide to ...

• troubleshoot it with scanner data
• reset it with scanner fault clear
• reboot it by disconnecting both batteries at once
• replace it by calling your dealer connection $$$$
• resolder it by calling you solder buddy

You need to get that stolk working to get gearbox in "D" drive else stuck in "P".


Progress is about getting the right focus to carry individual steps... congrats!

 

How might I go about tackling the steering column module?

 

This is what ChatGPT said…I see the new scan. The key faults are still pointing in the same direction: a communication problem centered around the shift system and drivetrain CAN path, not just a bad shifter by itself.



Most important faults in this report:

• “Communication With The Electronic Selector Lever Module Has A Malfunction.”
• “No CAN Message Was Received From Control Unit N15/5 (Electronic Selector Lever Module Control Unit).”
• “No CAN Message Was Received From Control Unit Motor Electronics.”
• “Communication With The Intelligent Servo Module (ISM) Has A Malfunction.”

The scan also shows these modules present in the vehicle network list:

• EZS / electronic ignition lock
• ECM / engine control module
• TCM / transmission control module
• CGW / central gateway
• ISM / shift module

What that usually means in plain English:

The car is losing communication between the selector lever side, the ISM, and at least part of the drivetrain network. When you see both selector lever/ISM faults and missing CAN messages, the likely causes move toward:

• low voltage or unstable supply to one of those modules
• bad ground
• CAN wiring fault
• connector corrosion / loose connection
• failed ISM
• less commonly, gateway/EZS-side communication issue

Because the report also says no CAN message from Motor Electronics, I would not jump straight to “replace the shifter.” That pattern can happen when one module is offline, shorted, underpowered, or pulling down the bus.



The other notable non-shift faults are:

• AC humidity/temperature sensor internal electrical fault
• multicontour seat pneumatic pump fault
• “connecting cable is not connected” fault entry

Those look more secondary right now unless they share a power/ground issue with the main network problem.



Best diagnostic order from here:

1. Verify battery voltage at rest and with ignition on.
2. Check power and ground at the ISM and selector lever related modules.
3. Inspect CAN wiring/connectors between ISM, EZS/CGW, and drivetrain side.
4. Check under-seat / console / moisture-prone connector areas if applicable.
5. See whether one module goes offline completely or intermittently when scanned individually.

Based on this report alone, my working diagnosis is:

network/power/ground fault affecting ISM-selector lever communication, with possible module failure but not yet proven.



Upload the detailed per-module pages if you have them, especially:

• ISM
• EZS
• CGW
• ECM
• TCM

Then I can narrow it down much further. Also, here’s the scan file you uploaded:
I would not treat the steering column module as the first thing to replace yet.



Your screenshots point more to a DIRECT SELECT / selector-lever signal problem chain than a clearly proven bad SCCM/stalk.



What your screenshots show:

• ISM A80 has:
  • P179D85 “Redundancy system for DIRECT SELECT was activated. There is a signal above the permissible limit value.”
  • P179D00 “Redundancy system for DIRECT SELECT was activated.”
• ECM shows:
  • 1433 “Communication with the electronic selector lever module has a malfunction.”
• TCM shows:
  • U0103 “No CAN message was received from control unit N15/5.”
    And your earlier scan also showed selector/ISM/CAN communication faults together.

That combination usually means one of these:

1. stalk/direct-select input problem
2. wiring/connector issue between stalk/SCCM and downstream modules
3. low voltage / unstable power during actuation tests
4. ISM still intermittently unhappy even though it reset
5. less likely, the SCCM itself is bad

Also, your scanner repeatedly popped “Communication failure… check vehicle voltage >11V” during actuation. With only 12.5 V shown KOEO, that is not horrible, but it is not a strong buffered diagnostic voltage either. A Mercedes can get picky during module communication tests.





Best way to tackle the steering column module





Do it in this order:





1) Stabilize voltage first





Put the car on a real charger/power supply, not just battery alone.

• ignition on, engine off testing can drag voltage down
• aim for a stable support voltage while scanning/actuating

Then:

• clear codes
• cycle ignition
• rescan
• rerun SCCM/ISM communication tests

If the SCCM fault disappears with stable voltage, that saves you a lot of chasing.





2) Treat the DIRECT SELECT stalk as a signal source, not automatically the bad module





Because P179D85 says signal above permissible limit, I’d suspect:

• short to power
• biased signal line
• internal stalk fault
• connector/contact issue at steering column module area

So inspect:

• steering column stalk connector
• SCCM connectors
• any pin spread, corrosion, bent terminals, looseness
• harness where the column tilts/telescopes, if applicable

3) Scan the SCCM/N80 directly





You want the exact fault text/code inside SCCM, not just the summary list.

That matters a lot. For example:

• “implausible signal”
• “open circuit”
• “short to positive”
• “CAN communication fault”
• “internal fault”

Those mean very different things.





4) Look at live data for selector lever/stalk status





If your Launch will show actual values, check things like:

• lever request / selector request
• park/reverse/neutral/drive command
• plausibility or redundant channel values
• status change when you move the stalk

If moving the stalk gives:

• no change at all → possible stalk/SCCM input issue
• erratic/jumping values → possible worn stalk or bad connection
• normal values but ISM/TCM still complain → more likely downstream communication/wiring/ISM issue

5) Do a physical wiggle test while watching live data





Key on, scanner in live data:

• gently move the selector stalk
• gently move column trim/harness area
• watch for dropouts or impossible values

That can expose an intermittent harness or connector fault.





6) Don’t ignore that the ISM only “reset to normal mode”





That does not prove it is healthy.

It only proves the module could be commanded/reset at least once.



Since you still have:

• ECM selector lever comm fault
• TCM U0103
• prior ISM/selector/CAN faults

the chain may still be:

stalk input fault → ISM redundancy → network complaints

or

network/wiring issue → false selector faults





Practical decision tree





If I were standing there with the car, I’d do this:



A.

Charge/support voltage, clear codes, key cycle, rescan.



B.

Read the full SCCM/N80 code(s).



C.

Read live data for the selector stalk request.



D.

If stalk data is implausible or missing:

• inspect connector/wiring at SCCM/stalk
• then suspect stalk/SCCM assembly

E.

If stalk data looks normal but ISM/TCM still complain:

• shift focus back to ISM wiring / CAN / power / ground

My current read





Based on what you’ve shown, I would say:

• possible SCCM/stalk problem: yes
• proven bad SCCM needing replacement: not yet
• first attack: voltage support, direct SCCM fault details, live data, connector inspection

The most important next piece is a screenshot of the actual SCCM/N80 detailed fault code page and, if available, live data for the DIRECT SELECT lever request. That would narrow this down fast.

 

A whole lot of that makes great perfect sense except at least this:While this is not false it is generic and not applicable here.

GPT badly overlooks the importance of ECM/TCM/SCM modules being on different buses across CGW. Luck is not a lottery

Based on the input of your scan reports, it seems GPT is able to provide guidance.

How is GPT gonna deal with SCM...?

 

oh ChatGPT is far from perfect it’s amazing the simple things that it gets wrong, although it does provide some good insights where I need a different point of view.

I went into the direct select module and performed an actuation test and it seems to be shifting just fine as well as the automatic transmission mode button next to the command knob. Well, I’m glad it’s not the direct select lever module, it’s looking more and more like a wiring issue and I’m no electrician.

 

I’m going to ask one of the maintenance guys here at the apartment complex I live at to activate an electrical outlet near my vehicle so I can keep a charger on it instead of having to take the battery out of my vehicle and bring it into my apartment to charge.

There’s plenty of outlets and none of them are powered:/

 

Latest scan…

 

From this latest DTC report the next best target seems like :

-1- SCM to get your car out of "P".
-2- FAN to get necessary engine cooling.

SCM is one of the module featuring the amazin' solderless pin you've meet in the EZS.

This module share similar fare with optical sensor and pins ... needs "clean" table to open up. It is a bit on the delicate fragile side.

> You can decide to ...

• troubleshoot it with scanner data
• reset it with scanner fault clear
• reboot it by disconnecting both batteries at once
• replace it by calling your dealer connection $$$$
• resolder it by calling you solder buddy

You need to get that stolk working to get gearbox in "D" drive else stuck in "P".


Progress is about getting the right focus to carry individual steps...

 

I’ve actuated every function of the steering wheel, including the steering angle sensor, direct select stalk , paddle shifters, cruise control stalk etc.

It recognizes every single shift from direct select so I think we’ve ruled that out.

One of my neighbors nephews is a Mercedes technician, and he thought it was a conductor plate, but the data doesn’t point us towards that being the main cause… or does it?

 

glad you could see though that... nothing points to conductor-plate for a rebuilt tranny job. Mighty scanner saved you another big bundle !!

You have successfully tested all functions of SCM: ok - More money well saved right there!!

Now you can guess there is something flakey disrupting the CAN between: SCM < CGW > ECU + ISM.
It can be a few things, to begin by bad Footwell GND post shared by F-SAM/CGW or something bad on the SCM bus such as a failing module: OCP,... to be Unplugged at bus-bar.

Let's troubleshoot your unknown sleepless fan issue.

 

I think I mentioned this before, but as far as the cooling fan is concerned, it works just fine with the engines on. It’s when the vehicle is off and locked. It will randomly kick on draining the main battery. I’ve replaced the AC pressure switch and know that it could also be an ECU issue. The reason we’re getting a code for it right now is because I have it unplugged.

 

do you think the sleepless fan could be causing my other can issues?

 

the short answer is: not likely.

The fan is not networked, it is home-runned to be turned off by ECU with 10% duty cycle Pulse.

Again here scanner is going to pay for itself by helping you with fan dedicated test menu. From there you can activate fan to see that it responds or not while plugged in.

The fan live data with lead you to understand what's requesting your fan activity.

 

that is an interesting clue.
The fan works well until it eventually wakes up randomly.
We can suspect something got wet with oil or water to interrupt the fail safe always active fan signal.
(Now issue less likely have to-do with A/C line pressure sensor).