Im having trouble with starting my 2014 E550. Started with key goes in, but I don’t hear the ‘grab’. Able to turn it all the way but nothing. Lights and everything work. Service Menu says battery at 11.7V but I replaced with a new one anyway. After replacing battery, same issue. I decided to try again by stepping on the brake while turning the ignition, then it...magically got the car started. Drove it around and starts again, no problem. However I still don’t get the key ‘grab’. Any idea what could be the problem? I’m driving home tomorrow and will bring to a mechanic, but wondering if this will leave me stranded - or if I should be checking something?

 

It sounds like EIS/EZS - ignition switch - issues. Do you have a scanner that can read codes?

 

Ok what am I missing? On my 2016 (same facelift model as yours), it will not start unless I STEP ON THE BRAKE, first. Says so in the manual. No magic involved.

 

Just to note, I do not have keyless go. Will see if a local shop can read codes tomorrow and will report back if I have success.

 

No need to press the brake to start it with the key. I have KeylessGo but I use the key to start the ignition (preference).

 

Sorry. MB is so concerned with accidental roll-backs, I thought you needed to step on the brake for either method. Carry on...

 

Following up, it was just the key. Found the spare and it worked fine. But to note, I read the manual and it says even a bad/wrong key will turn in the ignition...didn’t know that!

 

Problem came back, it happens when it’s freezing temperatures, when car is cold sitting outside. When car is warm or temperatures are over freezing, no problem. Finally got a code U0101, fault with communication with transmission control module. Is there a sticky relay I should be checking?