2014 CLS550 – Central Display Completely Dead (4 Years Troubleshooting… Need Ideas
Thread Starter
Newbie
Joined: Oct 2021
Posts: 13
Likes: 3
From: Kentucky
2014 CLS550
2014 CLS550 – Central Display Completely Dead (4 Years Troubleshooting… Need Ideas
Hey everyone,
I’m hoping someone here has run into this before, because I’m officially out of ideas. My 2014 CLS550’s central display (the COMAND screen) has been completely dead for years. No backlight, no flicker, no logo — nothing. It behaves like it’s unplugged, even though it isn’t.
I’ve been trying to solve this off and on for close to four years, and this forum is my last stop before I give in and take it to the dealer.
Xentry Diagnostics
Under A40/3 – COMAND APS, I consistently get:
C255 – Communication with the central display has a malfunction
I’ve run through all the guided tests in Xentry, including:
At This Point…
I’m stuck. The CAN lines check out, power checks out, fuses check out, and even swapping hardware hasn’t made a difference. Xentry only gives me the same communication fault over and over.
Before I hand this over to the dealer (and likely get a painful invoice), does anyone have ideas on what else I can test? Hidden modules, known wiring issues, grounding points, or anything specific to the W218 that could cause a nonfunctioning display?
Any help or direction would be hugely appreciated.
I’m hoping someone here has run into this before, because I’m officially out of ideas. My 2014 CLS550’s central display (the COMAND screen) has been completely dead for years. No backlight, no flicker, no logo — nothing. It behaves like it’s unplugged, even though it isn’t.
I’ve been trying to solve this off and on for close to four years, and this forum is my last stop before I give in and take it to the dealer.
Xentry Diagnostics
Under A40/3 – COMAND APS, I consistently get:
C255 – Communication with the central display has a malfunction
I’ve run through all the guided tests in Xentry, including:
- Checked Fuse 11
- Detached connector 2 from A40/8 and verified voltage — correct
- Verified continuity between (A40/8) 2.8 → CAN-HIGH (X30/35) — good
- Verified continuity between (A40/8) 2.4 → CAN-LOW (X30/35) — good
- Pulled Fuse 11 for 30+ seconds
- Checked power at (A40/9) x1.1 and x1.2 — battery voltage present
- Verified continuity between (A40/9) 1.3 → CAN-HIGH (X30/35) — good
- Verified continuity between (A40/9) 1.4 → CAN-LOW (X30/35) — good
- Replaced the central display with a used unit from eBay
- Replaced the COMAND head unit with another used unit from eBay
- Replace LVDS between COMAND and display
- Disconnected the battery for weeks at a time
At This Point…
I’m stuck. The CAN lines check out, power checks out, fuses check out, and even swapping hardware hasn’t made a difference. Xentry only gives me the same communication fault over and over.
Before I hand this over to the dealer (and likely get a painful invoice), does anyone have ideas on what else I can test? Hidden modules, known wiring issues, grounding points, or anything specific to the W218 that could cause a nonfunctioning display?
Any help or direction would be hugely appreciated.
Out Of Control!!
Joined: Apr 2019
Posts: 12,006
Likes: 6,830
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
TROUBLESOME SLEEPY DISPLAY(S)
Hey everyone,
I’m hoping someone here has run into this before, because I’m officially out of ideas. My 2014 CLS550’s central display (the COMAND screen) has been completely dead for years. No backlight, no flicker, no logo — nothing. It behaves like it’s unplugged, even though it isn’t.
I’ve been trying to solve this off and on for close to four years, and this forum is my last stop before I give in and take it to the dealer.
Xentry Diagnostics
Under A40/3 – COMAND APS, I consistently get:
C255 – Communication with the central display has a malfunction
I’ve run through all the guided tests in Xentry, including:
At This Point…
I’m stuck. The CAN lines check out, power checks out, fuses check out, and even swapping hardware hasn’t made a difference. Xentry only gives me the same communication fault over and over.
Before I hand this over to the dealer (and likely get a painful invoice), does anyone have ideas on what else I can test? Hidden modules, known wiring issues, grounding points, or anything specific to the W218 that could cause a nonfunctioning display?
Any help or direction would be hugely appreciated.
I’m hoping someone here has run into this before, because I’m officially out of ideas. My 2014 CLS550’s central display (the COMAND screen) has been completely dead for years. No backlight, no flicker, no logo — nothing. It behaves like it’s unplugged, even though it isn’t.
I’ve been trying to solve this off and on for close to four years, and this forum is my last stop before I give in and take it to the dealer.
Xentry Diagnostics
Under A40/3 – COMAND APS, I consistently get:
C255 – Communication with the central display has a malfunction
I’ve run through all the guided tests in Xentry, including:
- Checked Fuse 11
- Detached connector 2 from A40/8 and verified voltage — correct
- Verified continuity between (A40/8) 2.8 → CAN-HIGH (X30/35) — good
- Verified continuity between (A40/8) 2.4 → CAN-LOW (X30/35) — good
- Pulled Fuse 11 for 30+ seconds
- Checked power at (A40/9) x1.1 and x1.2 — battery voltage present
- Verified continuity between (A40/9) 1.3 → CAN-HIGH (X30/35) — good
- Verified continuity between (A40/9) 1.4 → CAN-LOW (X30/35) — good
- Replaced the central display with a used unit from eBay
- Replaced the COMAND head unit with another used unit from eBay
- Replace LVDS between COMAND and display
- Disconnected the battery for weeks at a time
At This Point…
I’m stuck. The CAN lines check out, power checks out, fuses check out, and even swapping hardware hasn’t made a difference. Xentry only gives me the same communication fault over and over.
Before I hand this over to the dealer (and likely get a painful invoice), does anyone have ideas on what else I can test? Hidden modules, known wiring issues, grounding points, or anything specific to the W218 that could cause a nonfunctioning display?
Any help or direction would be hugely appreciated.
Nobody else is going to go deeper than you've gone already.... let's get this completed.
The paradox here is everything checks out well but COM error is still being pointed out by Xentry.
Is this particular network node available at the bus bars ?
Do you have use of the electric diagram related to this module - Let us see how this is all wired.
Any way you can install original COMAND back in place since the replacement test unit did not help (while all power disconnected - Never "Plug & Play"!).
I think we can focus on the network alone since you have Power+GND and xentry points to network.
Q: what are other modules sharing that same network (CAN-?E1?) that can collapse it ??
Can we get a comprehensive chassis scan report to survey what other chaos is seeded.
Last edited by CaliBenzDriver; Mar 22, 2026 at 11:21 PM.
Thread Starter
Newbie
Joined: Oct 2021
Posts: 13
Likes: 3
From: Kentucky
2014 CLS550
trigital - Thank you for your response. With as many times as I have had this thing in and out, it is plausible that I installed it incorrectly. However, I took a look at the LVDS and it is keyed so it is only able to be installed one way.
Last edited by toones; Mar 23, 2026 at 12:47 PM.
Thread Starter
Newbie
Joined: Oct 2021
Posts: 13
Likes: 3
From: Kentucky
2014 CLS550
Very good job so far... this should be working by now!
Nobody else is going to go deeper than you've gone already.... let's get this completed.
The paradox here is everything checks out well but COM error is still being pointed out by Xentry.
Is this particular network node available at the bus bars ?
Do you have use of the electric diagram related to this module - Let us see how this is all wired.
Any way you can install original COMAND back in place since the replacement test unit did not help (while all power disconnected - Never "Plug & Play"!).
I think we can focus on the network alone since you have Power+GND and xentry points to network.
Q: what are other modules sharing that same network (CAN-?E1?) that can collapse it ??
Can we get a comprehensive chassis scan report to survey what other chaos is seeded.
Nobody else is going to go deeper than you've gone already.... let's get this completed.
The paradox here is everything checks out well but COM error is still being pointed out by Xentry.
Is this particular network node available at the bus bars ?
Do you have use of the electric diagram related to this module - Let us see how this is all wired.
Any way you can install original COMAND back in place since the replacement test unit did not help (while all power disconnected - Never "Plug & Play"!).
I think we can focus on the network alone since you have Power+GND and xentry points to network.
Q: what are other modules sharing that same network (CAN-?E1?) that can collapse it ??
Can we get a comprehensive chassis scan report to survey what other chaos is seeded.
The quicktest shows 3 faults:
(1) the A/C is low on freon. I have verified with guages that it is in fact low on freon
(2) the multifunction camera has a short in the window heater. This fault existed before the COMAND display went out.
(3) the COMAND APS
Out of desperation, I also replaced the auxillary battery as I read somewhere that can impact the SAM. Obviously that did not fix it.
What do you think my next steps should be?
Out Of Control!!
Joined: Apr 2019
Posts: 12,006
Likes: 6,830
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Thank you for your response! I have attached the quicktest scan as well as the wiring diagram for the COMAND. If these are not the best tests for troubleshooting, please let me know.
The quicktest shows 3 faults:
(1) the A/C is low on freon. I have verified with guages that it is in fact low on freon
(2) the multifunction camera has a short in the window heater. This fault existed before the COMAND display went out.
(3) the COMAND APS
Out of desperation, I also replaced the auxillary battery as I read somewhere that can impact the SAM. Obviously that did not fix it.
What do you think my next steps should be?
The quicktest shows 3 faults:
(1) the A/C is low on freon. I have verified with guages that it is in fact low on freon
(2) the multifunction camera has a short in the window heater. This fault existed before the COMAND display went out.
(3) the COMAND APS
Out of desperation, I also replaced the auxillary battery as I read somewhere that can impact the SAM. Obviously that did not fix it.
What do you think my next steps should be?
Just lose that one Display issue and you'll be golden.
Case in points: there does not seem to be collateral bugs acting jointly to tank your display module.
Your MFK has poor connections. Either ignore, replace or resolder pressed pins. This won't your display.
very minimal issue
Bottom line: spend more time to focus on the DISPLAY module only.
Use your diagram pages to triple-check:
/ all Power signal live
/ GND can draw power
/ Network has correct levels.
You may be simply dealing with bad wiring connection.
Last edited by CaliBenzDriver; Mar 26, 2026 at 06:27 PM.
Thread Starter
Newbie
Joined: Oct 2021
Posts: 13
Likes: 3
From: Kentucky
2014 CLS550
I need a little more help in understanding this as I attempt to do more troubleshooting. I have verified power and ground, which leaves network. I assume that by network, you mean the Signal Acquisition Module (SAM).
Does the SAM act as a "smart switch" that turns on the device (like the display), so even though the device has power and ground, if the SAM doesn't send a signal, it will not turn on?
If that is the case, how do I determine the voltage that should be sent from the SAM to the device (in this case the display)?
Thanks!
Does the SAM act as a "smart switch" that turns on the device (like the display), so even though the device has power and ground, if the SAM doesn't send a signal, it will not turn on?
If that is the case, how do I determine the voltage that should be sent from the SAM to the device (in this case the display)?
Thanks!
Trending Topics
Out Of Control!!
Joined: Apr 2019
Posts: 12,006
Likes: 6,830
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
I need a little more help in understanding this as I attempt to do more troubleshooting. I have verified power and ground, which leaves network. I assume that by network, you mean the Signal Acquisition Module (SAM).
Does the SAM act as a "smart switch" that turns on the device (like the display), so even though the device has power and ground, if the SAM doesn't send a signal, it will not turn on?
If that is the case, how do I determine the voltage that should be sent from the SAM to the device (in this case the display)?
Thanks!
Does the SAM act as a "smart switch" that turns on the device (like the display), so even though the device has power and ground, if the SAM doesn't send a signal, it will not turn on?
If that is the case, how do I determine the voltage that should be sent from the SAM to the device (in this case the display)?
Thanks!
Use the diagram of Display to test all necessary Power + GND and possibly data.
With all that... module should run and communicate with scanner - Does it ??
BLOWER FLTR !!!!
Display is a hot module that is cooled by a small blower that has a tiny air filter that gets dirty plugged up.
Before you replace a new display, service the air cooling stream. Remove the passenger side glove box, look up to the left.
MB World Stories
The Best of Mercedes & AMG
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
