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Peter Zavarelli
Peter Zavarelli, Auto Mechanic
Category: Car
Satisfied Customers: 31119
Experience:  Technical Consultant at Just Answer
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I have a 2012 Mercedes C250 which is suffering from multiple

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I have a 2012 Mercedes C250 which is suffering from multiple intermittent electrical failures or malfunctions, with the symptoms being such as one front headlight and one tail light working, hi fi systems does not work during the fault condition, front passenger Neck Pro head restraint malfunction, driver side Neck Pro head restraint malfunction, LED daylight running light failure,CAN communication with Traction control, ESP systems and Air conditioning system malfunction, and various other CAN comms failures also something called a 30g power supply is less than 7.5 v....but the most annoying part is being Automatic it will not allow you to engage drive, so is stuck in park. As this is intermittent when the fault clears, all the systems work as normal.
The car is with my Mercedes specialist at the moment and he has checked the stored data but cannot advise me as to what might be the common fault that's causing the multiple failures.
Any advise would greatly appreciated.
Thanks in advance.

Hi, my name is ***** ***** I will be happy to assist with this today.In some cases, I may need more info to assist better.I apologize for any delay.

The circuit 30 power supply only being 7.5 volts will cause all of these issues here.It should be the same voltage as the battery which is around 12 volts.I recommend having all fuses checked in all fuse panels for any blown fuses that may be causing low voltage.If all fuses are o.k. then wiring needs checked leading from each fuse panel to see if any wiring is found to be faulty or damaged needing repaired or replaced.Low voltage causes all kinds of electrical faults intermittently.If the voltage issue is intermittent with the electrical faults here this may be due to a loose or corroded battery cable needing cleaned and tightened at or leading from the battery, the battery itself with an internal shorted or dead cell causing intermittent low voltage or the alternator itself at fault needing replaced.

These all need to be checked into to then locate and repair this issue here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service, your 5-star rating is appreciated ( should be a link to click on here or above).You can rate at any time and we can continue to work on your question as this will not close out your question.I work on delivering the best answer and help here but in some cases, it can be difficult to do without seeing the vehicle.

Thanks Pete

Customer: replied 1 month ago.
Hi Pete, thanks very much for your advice it help point my tech in the right direction. We’ve decided to replace both batteries as I have also noticed the stop/start system doesn’t seem to work anymore and both are almost 6 years old, and we’ll see if this clears the problem.

You're welcome

Let me know if you need anything else and feel free to rate my help here or above ( should be a link to click on ) as this is how I receive credit for my time, this can be done at any time and you can still come back here and reply if needed.Your 5-star rating is appreciated

Thanks Pete

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