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Hi All! First post on this forum...in anticipation, thanks to all who respond!
While driving home last night, my 2014 E350 suddenly started cycling through all kinds of fault messages on the dash...
- Pre Safe Inoperative
- Cruise Control Inoperative
- Active Blind spot assist inoperative
Also, speed indicator fluctuated for a couple minutes before dropping off to indicate 0 MPH.
Brake light ON and of course, Check Engine icon was ON too.
Also, Steering Wheel became stiff - so power steering likely not operating.
Seemed like electrical glitches associated with the control system rather than one specific sensor.
So, I parked and turned OFF car for a couple minutes. But, problems persisted after restarting.
Needed to get home, so drove on another 10mins with the faults flashing and car beeping. Haven't turned it ON again...
No recent repairs. Car serviced about 3 months ago. Has been raining hard last couple days where the car is parked in the open...but nothing new or unusual otherwise!
Any idea what might be happening?
Gotta start by pulling the CEL codes; check your ecu to see if there is oil in the ecu wire harness ... agreed that a more central unit or wire harness is affected...
rodents chewing through wire looms in warm engine bay on a cold rainy day would absolutely do this
check with your comprehensive auto insurance policy to see if this is covered IF it's rodent damage
Thanks PeterUbers!
Have set up an appt with my mechanic next week. Also ordered my OBD scanner...so one way or other will be getting the CEL codes shortly.
But, I was hoping for the kind of feedback you provided....good idea checking for oil around ecu wire harness. Will research online to determine where in my car to look for it.
Also was thinking that the specific set of faults might point to an issue with a particular wire harness...could be the ECU harness you mention, but what else could it be? Might even be the ECU itself or another electronic module (hopefully not! $$$). Hoping someone with specific knowledge will respond.
I'm technical so can do some mental diagnosis and troubleshooting. However, with cars, I have never done more than jump the battery or top off oil. Yet would hate to plunk down several $100 for something that required me to locate and reinsulate some frayed wires. I am willing to get my hands dirty, but will need some helpful pointers. So thanks!
Thanks PeterUbers!
Have set up an appt with my mechanic next week. Also ordered my OBD scanner...so one way or other will be getting the CEL codes shortly.
But, I was hoping for the kind of feedback you provided....good idea checking for oil around ecu wire harness. Will research online to determine where in my car to look for it.
Also was thinking that the specific set of faults might point to an issue with a particular wire harness...could be the ECU harness you mention, but what else could it be? Might even be the ECU itself or another electronic module (hopefully not! $$$). Hoping someone with specific knowledge will respond.
I'm technical so can do some mental diagnosis and troubleshooting. However, with cars, I have never done more than jump the battery or top off oil. Yet would hate to plunk down several $100 for something that required me to locate and reinsulate some frayed wires. I am willing to get my hands dirty, but will need some helpful pointers. So thanks!
look for animal evidence like fur or droppings and straight up chewed wire looms
2016 E350 4Matic wagon, 2019 Ford Expedition, 2019 Chevy Bolt EV
they aren't subtle around here. we were away for a week, came home, popped the hood on my wife's older Mercedes to check the oil and found this lovely...
Did manage to get in to see my mechanic Daniel on Saturday - I love this guy! Highly recommend him for residents of Santa Clarita valley, and north LA, CA! (https://www.yelp.com/biz/valencia-mb...anta-clarita-8)
When I drove out the car on Saturday, first time after parking it on Friday, the fault messages did not appear! However, a little while after I got into Daniel's shop they were flashing once again! So, the problems were intermittent and seemed to come on after the car/unit warmed up - pointing to a possible electronic issue.
CEL faults reported..
1) U0122 - Lost communication with Vehicle Dynamics Control Module
2) P0507 - Idle Air Control System ROM Higher than expected
Lost communication with VDC is the likely cause of all the 'Inoperative' faults. Couldn't see any obvious damage to the wiring harness going to the VDC. Disconnected VDC cable/harness from the VDC and checked the power going to VDC - both on lines that always have power and one that is active after ignition - all okay! Other connection pins would be carrying signals from VDC to ECU or other parts of the car, and it is possible for these other wires to be damaged. However, with at least two of the power wires having checked out alright, it is unlikely that multiple other wires, corresponding to the different faults, in the same harness are damaged. So, we decided it was more likely that the VDC unit was faulty...Daniel will be ordering that.
Will update this thread when we have resolution...hopefully it will help someone else!
BTW...another symptom of this situation is that the power/ignition button does not work after the car gets into this state. Removing the button and using the keyfob to turn ignition is the only way I could get the car ON again.
Did manage to get in to see my mechanic Daniel on Saturday - I love this guy! Highly recommend him for residents of Santa Clarita valley, and north LA, CA! (https://www.yelp.com/biz/valencia-mb...anta-clarita-8)
When I drove out the car on Saturday, first time after parking it on Friday, the fault messages did not appear! However, a little while after I got into Daniel's shop they were flashing once again! So, the problems were intermittent and seemed to come on after the car/unit warmed up - pointing to a possible electronic issue.
CEL faults reported..
1) U0122 - Lost communication with Vehicle Dynamics Control Module
2) P0507 - Idle Air Control System ROM Higher than expected
Lost communication with VDC is the likely cause of all the 'Inoperative' faults. Couldn't see any obvious damage to the wiring harness going to the VDC. Disconnected VDC cable/harness from the VDC and checked the power going to VDC - both on lines that always have power and one that is active after ignition - all okay! Other connection pins would be carrying signals from VDC to ECU or other parts of the car, and it is possible for these other wires to be damaged. However, with at least two of the power wires having checked out alright, it is unlikely that multiple other wires, corresponding to the different faults, in the same harness are damaged. So, we decided it was more likely that the VDC unit was faulty...Daniel will be ordering that.
Will update this thread when we have resolution...hopefully it will help someone else!
BTW...another symptom of this situation is that the power/ignition button does not work after the car gets into this state. Removing the button and using the keyfob to turn ignition is the only way I could get the car ON again.
A-- Tested Twice vs. None:
Don't rush to changing good untested parts to save time. In the end the repair will take more ressource in parts & time.
B-- EIS Snowball Party:
The main Ignition Switch acting up is your wake up call here. For some reason, the car VIP computers got pissed off from bad data stream and become unable to function safely.
It's uneasy to guess what exactly started initiated that snowball... I can guess the old EIS dusty opticals with unsoldered pins got unstable commanding front SAM power master that fouled the ECU that pissed off CAN-C VIP modules.
Essentially : the junk amazing ignition switch turns the car "ON/OFF" while you are driving.
It is carefully built to deliver the above experience in due time.
(unsoldered Transmission Shifter does not seem involved...LM.)
C-- POWER IS ESSENTIAL :
Before suspecting anything expensive, you need to double check for good power supply from ALTERNATOR and starter battery.
Without opening the driver door (it bumps up voltage to quick charge level) use a voltmeter to measure car voltage -Or more easily: listen to the sound of winding up/down front windows (without opening driver door!): Does that sound SLOW or normally FAST?
D-- FREE CAR CARE:
- Float charge your main battery full.
- Reboot the whole car by disconnecting batteries.
🤞
Last edited by CaliBenzDriver; Mar 6, 2023 at 04:53 PM.
Reason: EIS creating struggle
A-- Tested Twice vs. None:
Don't rush to changing good untested parts to save time. In the end the repair will take more ressource in parts & time.
B-- EIS Snowball Party:
The main Ignition Switch acting up is your wake up call here. For some reason, the car VIP computers got pissed off from bad data stream and become unable to function safely.
It's uneasy to guess what exactly started initiated that snowball... I can guess the old EIS dusty opticals with unsoldered pins got unstable commanding front SAM power master that fouled the ECU that pissed off CAN-C VIP modules.
Essentially : the junk amazing ignition switch turns the car "ON/OFF" while you are driving.
It is carefully built to deliver the above experience in due time.
(unsoldered Transmission Shifter does not seem involved...LM.)
C-- POWER IS ESSENTIAL :
Before suspecting anything expensive, you need to double check for good power supply from ALTERNATOR and starter battery.
Without opening the driver door (it bumps up voltage to quick charge level) use a voltmeter to measure car voltage -Or more easily: listen to the sound of winding up/down front windows (without opening driver door!): Does that sound SLOW or normally FAST?
D-- FREE CAR CARE:
- Float charge your main battery full.
- Reboot the whole car by disconnecting batteries.
🤞
Thanks! All good suggestions. Will try to follow and update.
Have the car working again without any faults! But whether its fixed is still a question!
@CaliBenzDriver you may have been right about the power. After a week of sitting in the garage, when I tried to get the car started again, the battery was dead. First thought was "is there a short in the system that drained the battery?". When checking out the battery, I noticed it was 5 years old (3/18). So could be, the battery was going bad and causing the problems. Was the battery the cause or the symptom?!
Called AAA, jumped the battery and got it running. After the jump, as I kept the car running to charge the battery, the fault messages were still flashing. However, as soon as I started driving, they disappeared - likely the sensors began sensing movement, VDC received signals and started communicating with whoever needed those signals! So no more active faults - the 'check engine' icon was still lit from faults in memory.
My mechanic Daniel had ordered and yesterday received a used VDC. The plan was to try it out and see if the faults went away - so that is where I drove to. But he suggested replacing the battery first - with 5 years on it, might need to be done sooner or later (First battery was replaced in 3/18, after 4 years, 2014 - 2018). With the new battery, we drove a bit, waited for faults to show up - they didn't! Cleared all faults from memory. Then we agreed not to change anything else, just run the car for a few days to see if the new battery fixed the problem.
This morning the car still did not report any faults. If it was the battery, hopefully they'll not appear again. I'll report here once again if that happens. If I don't add anymore to this thread, it will be because everything works fine now!
Have the car working again without any faults! But whether its fixed is still a question!
@CaliBenzDriver you may have been right about the power. After a week of sitting in the garage, when I tried to get the car started again, the battery was dead. First thought was "is there a short in the system that drained the battery?". When checking out the battery, I noticed it was 5 years old (3/18). So could be, the battery was going bad and causing the problems. Was the battery the cause or the symptom?!
Called AAA, jumped the battery and got it running. After the jump, as I kept the car running to charge the battery, the fault messages were still flashing. However, as soon as I started driving, they disappeared - likely the sensors began sensing movement, VDC received signals and started communicating with whoever needed those signals! So no more active faults - the 'check engine' icon was still lit from faults in memory.
My mechanic Daniel had ordered and yesterday received a used VDC. The plan was to try it out and see if the faults went away - so that is where I drove to. But he suggested replacing the battery first - with 5 years on it, might need to be done sooner or later (First battery was replaced in 3/18, after 4 years, 2014 - 2018). With the new battery, we drove a bit, waited for faults to show up - they didn't! Cleared all faults from memory. Then we agreed not to change anything else, just run the car for a few days to see if the new battery fixed the problem.
This morning the car still did not report any faults. If it was the battery, hopefully they'll not appear again. I'll report here once again if that happens. If I don't add anymore to this thread, it will be because everything works fine now!
had the same issue like yours Jay.
changed the Battery, everything seemed fine for 2 weeks. Temperature dropped to -10 today and the warnings came back.
scanned up got 50 errors, all were communication errors.
really clueless now.
had the same issue like yours Jay.
changed the Battery, everything seemed fine for 2 weeks. Temperature dropped to -10 today and the warnings came back.
scanned up got 50 errors, all were communication errors.
really clueless now.
Go ahead and open a new thread dedicated to your particular issue - Describe your findings.
⚡
Great lesson in Mercedes repair!
Remember this, it will serve you well and welcome Cali to the rescue again.
I am always happy to help relieve forum friends from a couple different types of MB PITA. MB sofistication: one problem hides another...
The battery is on the receiving end of troubles, not the center piece!
Low voltage dishes out glitches that create faults that soft crash F-SAM into draining BATT until rebooted for free.
Fixing multi-tier Benz issues brings us all the way to SCM and EIS that are built to generate chaos on the network. I can testify of... when fixed, W212 (and siblings chassis) become better behaved smooth cars.
Good trouble free cars are no bargain to buy. We can enjoy MB for all its learning challenge & opportunities.
Last edited by CaliBenzDriver; Mar 14, 2023 at 08:07 PM.
Go ahead and open a new thread dedicated to your particular issue - Describe your findings.
⚡
will do. I just realised I changed the main battery, however, I never changed the auxiliary battery. Could this be the problem? I read, it is responsible for the elec components such as blind spots and sensors.
@JayShah did you change both the batteries?
thanks
Pretty sure the auxiliary battery in your car runs the accessories while the car is off in start/stop mode, Just curious, did you check under the front floor mat for water intrusion? You mentioned its been raining a lot, maybe pull out the mats and check under the carpet?
AUX + MAIN batts connected by SSR/Diodes conduction
Originally Posted by pierrejoliat
Pretty sure the auxiliary battery in your car runs the accessories while the car is off in start/stop mode, Just curious, did you check under the front floor mat for water intrusion? You mentioned its been raining a lot, maybe pull out the mats and check under the carpet?
Having a low MAIN voltage qualify to automatically over tax the AUX battery. SSR2 AUX + SSR1 MAIN disconnects
Both BATT's are connected through SSR's that are bypassed by internal diodes.
When the running voltage is low the AUX diode conducts power to guarantee a minimum. Unfortunately it is small and not able to supply long-term power. Same is true with MAIN compared to ALT.
The Main batt SSR is used to disconnect main batt during the start phase. This automatically puts AUX to work through it's SSR diode bypass.
My point here is that low car voltage is what directly seals the faith of AUX because it automatically feed circuit through diode under lower voltage than itself.
Float your main batt is a pretty good practice. For storage simply disconnect both (AUX then MAIN).
Last edited by CaliBenzDriver; Mar 15, 2023 at 03:22 PM.
Hi , just saw this is an old thread and im having the same issues with my car and a couple other stuff. Can you point me to where the dvc is located ? Thanks
Hi , just saw this is an old thread and im having the same issues with my car and a couple other stuff.
Can you point me to where the dvc is located ? Thanks
what sort of troubleshooting have you done to land on a dvc issue?
What was your main concern?
what sort of troubleshooting have you done to land on a dvc issue?
What was your main concern?
My car is having the same issues as his and apart from that the transmission wont shift out of park, the ac controls dont work, Stereo doesn’t work either , as for troubleshooting I scanned for dtcs and it showed something about the vdc not communicating
My car is having the same issues as his and apart from that the transmission wont shift out of park, the ac controls dont work, Stereo doesn’t work either , as for troubleshooting I scanned for dtcs and it showed something about the vdc not communicating
that's what you need to focus on.
Sorry I'm not familiar with that topic.
Last edited by CaliBenzDriver; Dec 2, 2025 at 12:28 AM.
any idea what could be wrong? I checked all the fuses today and they all checked out fine , tomorrow ill check the relays to see what could be wrong . Ill check the vdc also.
any idea what could be wrong? I checked all the fuses today and they all checked out fine , tomorrow ill check the relays to see what could be wrong . Ill check the vdc also.
Let's not guess 100% : pls post the DTC scan report with english descriptions
Last edited by CaliBenzDriver; Dec 9, 2025 at 05:19 PM.
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Multiple 'Inoperative' faults on 2014 E350
Cali to the rescue again
