Hi! Everyone, so out of the blue when insert the key fob into the car to start it (I do not have keyless Go or start) nothing happens. When you first plug it in, you usually hear for a split second a mechanical whirring, which my mechanic tells me is a locking motor which is there to recognise the key. I do hear that and turning the key does nothing, no pre engine lights, no cranking nothing. The battery is fine no issues there, however after sitting for a day or two, I rang up my mechanic and he tells me that this "locking motor" will be replaced, its an expensive job and the new part requires programming from Germany as it seems. However, yesterday the car suddenly and after some tries decided to work and start. I came to my relatives place again here I didn't work(no whirring, no start, no response) I took the key fob out, clicked the unlock and lock buttons, and the key didn't work its LED wasn't turning on. I stepped out clicked again, nothing, rattled the key fob, once it did, plugged it back it and viola, car worked again. So did some googling. And it's easy enough and cheap to replace the battery of the key fob, is it possible that is the only issue? However, first time around when I got to know of the problem the key fob was working , it was unlocking and locking the car. Generic car articles don't apply to MBs hence why I am posting here. Any advice would be appreciated.

 

what year & model, and which set of options related to the locking system? i have the keyless start/go system on a 2016, so I do not know much about the more basic or earlier configurations.

 

it's w212, 2010 delivery, 2009 model. Like I said mine does not have the keyless go or start (push button) options.

 

I had this problem with my C320 (2001). Insert key, it makes its normal noise, but the key won't turn, or does nothing when it does turm. The battery in the fob works only to initiate remote functions. I'm told it plays no role in starting the car.

Inserting the fob in the EIS (Electronic Ignition System) starts a process of several checks within the car's systems to determine readiness to start. In my C320, the Transmission Control Module (TCM) was intermittently working correctly. When it failed its check, the car would not start. When it did start, the tranny went into limp mode, meaning a 7-mile drive to the mechanic in 1st gear. I can't say for sure that this is your problem, because the TCM is just one of many system checks performed. But it was a maddening series of trips to the Indy mechanic at 15 mph.

Once the TCM was replaced, there were other check problems (including parasitic drains) to run down, then the car started performing normally, seemingly on its own. The EIS has NOT been replaced. And 16 months later, the car starts normally every time.

Good luck with this... I can't wish this stupid scenario on anyone...

 

yes Google was also telling me I might have EIS problems, but my does turn but does not give any noise you experience. Yes you are right that key fob battery plays no role in this. *sigh* another day another problem in German cars. Will keep updated what happens next.

 

Battery in the key is only required for lock/unlock on non-keyless go models. Do you have another key to test with? It could be the key, EIS, ESL...

The steering wheel lock, ESL, is a semi-common failure and it will prevent starting the car. This is what your mechanic is referring to. You can “hack” them and replace the two-cent motor inside without re-programing. Sometimes the chip inside gets burnt due to the dead motor and requires total replacement.

 

^To confirm, your car should start with no battery in the key fob. I suspect the EIS needs replacement.