I keep getting stored faults with backup camera, missing message with Ignition Switch Module, and COMAND. In Xentry it shows a few instances with COMAND, but hundreds with Ignition Switch Module. I'm assuming the issue is in a CAN circuit, normally what "Missing Messages" means. but so far all connectors I can find appear good, I'm assuming a loose connection or some green crusties intermittently breaking connection.

First issue is location of bus bar, and the other is identifying if low speed or high speed CAN bus.

I put scope on both at Backup cam module, but no issues found, not even when open close door, turn car on off, start car, change gear selections nothing shows.

I cannot tap Ignition With Module without removing Steering column, and that process would pollute testing by moving wiring and further prevent intermittent failure, or total failure, still hiding fault location and wire.

Any help or debate is welcome.

BTW the backup camera never fails to operate normally, always turns on in screen in reverse except when COMAND unit is turned off.

 

It seems you are on right track, Steering column module. I think the next failure will be failure to change from park to any, R N or D. Shut the engine off, double click key fob, wait for cluster off, then restart, it will work again. --> CAN hung up with so many messages.

 

My issue is messages sent from Backup Camera Module are intermittently being lost on CAN lines to COMAND module and Ignition Switch Module. I only mentioned steering column because Service Instructions say to remove Steering Column to gain access to Ignition Switch Module. No codes, and all tests pass on Electronic Shifter and Shifter Switch Module. It's somewhere between backseat and dash, but I need to see what the ignition switch sees. I was hoping someone found a way short of pulling steering column as I may disturb the fault and it not fail again till some time later.

 

I think you are both in the right ballpark, doing circles around few unknowns, like myself.
I think we may have a fair chance to solve this excellent pickle!

We are working like blind ants trying to feel our way through with our limited intelligence.

My car has had this issue since the first week of service. Since then I have had to learn more than I wish I knew about this.


So far from my vantage, I can see the following.... :

The modern CAN RFK is actually correct about its faults (there has been many prior incarnation of rear cams).
These modules are acting up more so than RFK itself at the end of its long unshielded differential CAN lines.

Your time would be really well spent if ... you'd resolder the SCM and EIS but there's more to as well.
MB did a fantastic job in spinning this snowball.

What is the bus shared by RFK, SCM, EIS and COMAND... CAN-B or which is it??

These state of the art modules are in dire need of help for repair!!
So much much so both SCM + EIS help delay the TCU shift timings ("in affected cars") - Tranny SHIFT performance from poor shift to limp-mode is MB fare.

If you solve these RFK FAULTS you'll have a great Mercedes working like few... no part needed!
✌️


My current Assumption :
Something is causing CAN traffic jams near F-SAM that's affecting the VIP: ECU/TCU.
RFK is simply witnessing this chaos for us. Let's see where it leads us.
(Juan: remember how I say my COMAND boots super fast? My radio plays while the unit display still show splash star logo. I noticed because that was unusual)

So far, I have reworked painted GND and solderless pins, yoyo-ALT... next is try shielding noise out of CAN twisted pairs - My criterias:

1. VIP Lines (SAM, ECU, TCU, ESP, ...)
2. Long Lines (front to back to front)
3. High-Speed bus lines (CAN-C, ...)

I think this amazing struggle game is organized around POOR TRANSMISSION leading to packet loss.
Great inputs very welcomed...

 

I rechecked just to make sure my findings, and The codes are
U016887 Communication with the electronic ignition lock has a malfunction. The message is missing STORED,
U014287 Communication with the rear signal acquisition and actuation module has a malfunction. The message is missing STORED,
U014787 Communication with the control unit "Head unit" has a malfunction. The message is missing. STORED

Xentry does show the number of instances of the U016887 of 246 times, the U014787 for 72 times, no code in Xentry is showing up for U014287. But I see no faults for the ECU, TCU, EIS, or steering. Just the RFK codes.

Benzninja did look at it from the Xentry point of view, and he did update the software in the RFK. But outside of that no physical issues outside of these codes have shown.

The car actually performs perfectly, and no issues outside of these codes. We drive it 5 hours interstate to a doctor out of state every month and she is a dream to drive, I get 34 mpg on the highway, plenty of power. I could live without the RFK if it did quit, as I never really use it, but my OCD wouldn't let me.

 

It's good to hear your car has been under the care of the @BenzNinja - Now you can realize this is non-trivial.

Furthermore I had the power to RFK cut from R-SAM for couple month without any improvement related to this issue.
That is to say RFK does not cause the other chaos experienced with MY'14.
In fact, RFK actually helps us witness what is really happening quietly under-wrap.

Surprisingly other modules dealing with the same module pairs do not report faults... EIS/SCM are built to be marginal an RFK tags them as questionable but other modules are trained to ignore the errors caused by loose pins issues.

 

One would think that watching the messages on the scope would show up if other modules had issues related to connections. I am familiar with having to resolder pins in automotive modules. I use leaded solder to remove the fragile silver solder and reflow with more resilient leaded solder. Learned that trick from working on Guitar tube amps.

Are you saying you had this issue, were you seeing any failures with other systems. If so what did you observe, what should I look out for. I will remove RFK and check solder joints as you recommended. Possibly reflow while I'm there anyway. You mentioned SCM, Are you referring to the control module or the switch module?

I reread your message in my mailbox, for some reason made more sense. I'm not sure which CAN line I'm checking as the schematics I have are vague, and The page I have doesn't show everything on that buss. I miss having Alldata.

If I understand, you are suggesting reflowing solder in all the modules, correct? I'm all about "No parts required"

 

Yes, that's right we have improved a hand full of affected modules. You should rush to fix your steering control module pin and EIS - That will automagically helps your car steering hold center neutral on the highways. (Regardless of Distronic+) like its never done it before.
Right then, for me the big deal the tranny begun to shift in snaps (not chewing gum or bangs) at perfect timings.

Get busy read my signature. You will get well soon.

 

I did have an issue with steering at higher speeds holding center, but was a bent wheel, wasn't enough to vibrate but gave steering an off center feel. I rotated tire, plan on replacing soon. last 5 months steering has been perfect. The trans issue was shifting weird, but reset adaptations strategies, it too has been perfect for better than five months.

Like I said, car performs admirably. only issues are codes, no issues would be present if I'd not scanned system.

If I don't find anything with bus bar, I will look into broken solder joints in RFK module. If I don't find anything there I will check between RFK to camera connections and wiring, if nothing then, I can check the Keyless Go Module, the shifter switch, and the SCM, when I can get a breathing spot to remove the steering column, to see if mine may have looming issues with solder joints as your car.

 

I have not managed to disassemble my RFK Module itself for proper soldering. There's a high chance it is using loose pins... which only helps expedite poor connections.

My RFK has been reporting 2 and sometimes 3 faults since factory new.... meaning RFK does not need aging to become defective.

The only upside with this module is it doesn't seem to hurt nor help other computer troubles centered around the F-SAM.


While driving 5Hr long distance, you may want to display the battery sensor vitals on your dashboard.


Main Batt sensor: (+12.1V; -40Amps)
​​​​
Few of these excellent cars have an issue whereby the ECU deep drains the MAIN + AUX batteries uncontrollably to 11Volts, no DTC!
✌️

This takes place during the "12.6V Float stage" on long drives, roughly after 45 to 60 minutes.

The whole car voltage then uncontrollably swings below 12.0 Volts while driving:
12.6V, 12.3V, 12.1V, 12.0V, 11.8V, 11.3V...


This defect comes straight from factory 0-Miles and has no effective fix that I am aware of.
The workarounds are to restart the car during a roadside emergency or to simply disconnect the ALT-LIN to allow perfect self-control.

 

I have been unsuccessful at displaying voltages or amps on my screen. I've found a couple of instructions on how, just my car never changes to that option screen. I have a power point plug that displays volts, my volts were hitting 15 and 16 volts, so I hit up FCPeuro for a Voltage regulator. One of the carbon contacts was half as long as the other which was almost half as long as new. volts maintain between 14.6 and 14.8 now, will reach 15 if battery is below 12 on start. Battery is 3 years old, but drains fairly quick, Topdon tester says replace, I can use a smart charger and will bring battery to "Good" status, but is short lived. I've replaced the aux batt as it was dated 2013 and tested replace event after charging.

As far as loose pins, this all began with environmental concerns, problem is the solution has created problems where none existed before. Lead free solder takes higher temp to apply and remove, leaded solder is far stronger and is more resilient to vibrations. In auto, many ECU failures were due to broken solder joints, problem since the 90s. Guitar tube amps and electronics, vibrations from high volumes and zealous musicians coupled with lead free solder is a recipe of "Guaranteed employment" for repair techs.

As long as the module can be opened without damaging board, a good magnifying lens or camera (one used in electronics repair) sometimes just using a meter can help find faults. Take leaded solder apply to broken solder, then with solder wick remove all the solder, flux apply leaded solder and chances of repeat failure has been greatly reduced. Learn this on Jeep PCMs. Except they use to fill the computer with a sealer you had to remove before repair.

I would rather have loose pins than green crusties, as cleaning those connections are hit and miss, even with Stabilant 22. as most are so tiny and fragile and easy to damage by loosening proper pin drag on connector.

 

Glad you found us...
Looking for future Miles
​​​​​​

 

Finally found out how to get into this.

 

so now you've gained access to your battery sensor, you have a way to read what the ECU/ALT are doing.

Any voltage reading between 14.9V and 12.6V is perfectly good. Current shoukd go from 8Amp towards 1Amp: perfectly good!

If impacted everything looks great then turn into chaos after 45mn when the hot ECU goes unstable... hopefully not !
🤞

 

The voltage never exceeded 14.8 or 12.6. Amps started at 64amps once it dropped below 6amps, alternated between +10 amps and -7 amps to maintain 12.7 volts, except when lights were turned on the 13.4 volts amps still was +10 amps to -7 amps. My battery is 4 years old CCA tested @ 58% of rated. I charged with smart charger starting amps much lower and goes into computer control much faster. Spoke to a long time Mercedes Master Tech, said if no actual concerns, i.e. if car is not acting up in any way nothing to worry about, they can set codes as car ages, and only need to investigate when hard faults are set. I'm seeing soft faults, meaning computer will see variance outside set parameters, hard faults when something stops working as intended. He also said this car has seen those soft faults for 3 years ago and dealer found no issues during paid diagnosis. That was great information to have.

 

yes, I wouldn't loose sleep over the crazy camera.

You report on voltage seems pretty good. The 10 Amps say that the battery is actively charging up. It's not high enough to suspect you have "drained by driving" issue.

You've figured turning the headlights ON does request a fixed 13.5V car voltage.

A well charged battery will see very little charge current from 1Amp down to 0A after full charge... PERFECT!

 

After reading some of your fixes and watching videos you have posted, I think I come closer to understanding the relationship between the modules you previously mentioned. Before, I assumed you were just throwing stuff out there, but, the relationship of the data packets sent and received on all CAN lines will affect all others. I had no Idea they used press fit pins. I'm from old school NAVY, plenty of data lines with broken solder joints, oil wicking issues in electro-hydraulic systems there. Thanks for posting all of this. I am going to pull the SCM and have a look, take some measurements, and solder all the press joints. Just crazy. Thanks.

 

Which modules are storing the above DTCs ?
Can you let me know the module ID too and not just the name, more accurate that way if this module has sister models.

 

Surya, I am back in town now. Let's try to make some progress.


These 3 DTC's are regularly issued by "RFK": the rear Backup Camera with integrated CAN controller. Failed from factory, not a high mileage condition.


> Camera face-lift :
- On W212 prior to face-lift used a separate module hosted near rear seat to control both voltage and CAN lines.
- On face-lifts these functions are all integrated inside the camera itself. This is is what we are dealing with here.
​​​​​​

> Fixing RFK faults...:
I have this issue so I have looked into this a bit. I think it is of minor importance but interesting to figure out. I had RFK power cut-off at R-SAM, this did not seem to help other module chaos.
The modules involved here (EIS, R-SAM, COMAND) are pretty important to keep humming. Poor COMS cause high-retransmit, that consumes bandwidth, that creates bottleneck, that cause poor performance and snowball issues and luxurious chaos.... I like none of this lemonade.

We all like great shortcuts, unfortunately here a Firmware update does NOT help this!

The way the RFK module logic fails like clockwork but camera appears to work well, makes me think the issue may be .... :

1. long noisy twisted-pair of CAN lines or
2. wicked CAN levels with poor GND or
3. unfiltered noisy 12V power supply

Right now my favorite is #1: the noisy twisted CAN lines!
MB went to great length to exploit the noise generated by 3-Phase LPFP.
They use extra long Power/GND lines mixed within low signal lines. I've already added a local GND and separated harness cable by types (power, twisted, signals) near rear right passenger seat towards front/back.

​​​​​​My plan is to upgrade twisted-pairs to shielded cable:

1. the main CAN lines from F-SAM to bus-bar.
2. the bridge line between L+R bus-bars.
3. the long RFK lines to bus-bar.
4. Low speed CAN-B
5. high speed CAN-C!!

This should bring a lot of peace between F-SAM /R-SAM to tame the Voltage-Yoyo and the soft-crashing "F-SAM/CGW" module that stays awake.
​​​​​​

 

Oky doky, I will take a look at the wiring and CAN-BUS-es. My car does not have reverse camera

 

Which one is it ? Just to be sure.............

By looks of both files wiring diagram, the CAN BUS has nothing to do with video feed.
Perhaps CAN BUS B for diagnostic or some image layering instruction like the guided ruler/lines to N66/? module ?

 

Yes, you're exactly right!

- Video feed is analog through a quality shielded coaxial cable to COMAND/Display...

- RFK uses CAN-B for control and gather steering angle data from SCM or CGW.

- Knowing RFK complains about poor EIS COMS is chilling because these are important modules.

The codes are "STORED" because the condition happen intermittently.... that's consistent with noise, marginally low starting voltage

 

Cali,

MB CAN BUS wiring topology has baffled me, because it is very much like a STAR, which most CAN BUS engineers would not agree to.

The drop line or stub or wire set from X30/30 distributor block to the N66/2 RFK module is I believe the longest wire run in the entire car. Perhaps 2-3 meters.
This goes against most advice, which do not use an X30/30 distributor block , but instead uses main bus line (wire ) routed as close to the device/node and hence the drop line becomes shorter.

Remember once I measured one of the distributor block and it has a built-in resistor for all connections ? That is another fact I don't understand because most CAN bus 101 will want
resistors of 120 ohms ONLY at each ending wire of main bus line or at both ending nodes if they have resistor built in.





I am attaching 3 documents. You know data transmission better than me. Its ur cup of tea
See what you can gather from those documents.

 

Yeah, that seems to another issue, on low starting voltage. I don’t use it, or I try to keep it off, but the ECO light for stop/start function the light is always yellow after starting. The aux batt is new, the main batt is 3 years old, still tests good on a Topdon battery tester. But afte driving a bit it will turn green. Car starts fine, other than testing battery…I replaced aux because it did test “Replace” on tester, despite no message, but it was less than half the rated CCA.

Noise. I remember having to reroute wires on board ship due to noise, or induced voltage from adjacent wires. I read what you said about the coaxial cable.

On guitar amps this is something we do to fix noise. With one caveat. The grounding shield of the coaxial wire can only be grounded on one end to shield inner wire from induced A/C voltage. The best way to see the noise and if the shielding is effective or not is with a scope. I’m inclined to lean towards noise, as the frequency of the fault seen in the ESMi such a high rate with just one startup after clearing. I’ve yet to see it an active fault it’s so intermittent.

I fear the best way is to drop steering column to access ESM to see fault on scope.better for wiggle check wires too.

Anyway all is on back burner for now, seems with old age other ailments like chronic pneumonia has put me on a Nebulizer along with much bed rest. I had planned on snatching modules and rework solder joints, but my wife told doc, and he gave a “Oh, HELL NO” speech.

I still need to do my trans service, I call a few shops including dealer, and no one does it correctly, they only do a partial service, only 6 liters of fluid, they don’t drain converter or cooler. The dealer here says it’s not required despite manufacture procedures says otherwise. So I will need to do myself to get it done right.