Good evening, all! I have a bit of a tricky problem with my 2006 C230 on which I'm looking for advice.

Essentially: my C230 does not start correctly. I can successfully unlock the car and turn my key in the ignition with no problem. However, the car's start is not as expected--while the mechanical parts of my car (the engine) and some electric components (headlights/tail lights, front and rear overhead lights, and, weirdly, the radio) work immediately, most other electric components (the windshield wipers, heat, windows, and instrument cluster, including the speedometer, fuel tank indicator, odometer, and message center) do not work.

The car is theoretically drive-able in this state, although is unsafe (without wipers, turn signals, and speedometer); if I do drive it while the electric components are non-functioning, the odometer, trip tracker, and other metrics in the message center do not record my miles driven while the message center was out of service.

Depending on the temperature outside, I may be able to wait between 3 and 10 minutes, turn the car off, and then turn it back on immediately to get these electric components to start working. When it gets really cold (under 35 degrees Fahrenheit), I might not be able to get the instrument cluster and other components working at all, no matter for how long I wait for the car to warm up. In the warmer weather (when the day's nadir temperature was above 50 degrees F), I was able to start my car without problems every day.

I've experienced this problem intermittently since I purchased my car in fall 2015. Because it's winter and I now have to deal with this daily, I finally bit the bullet and brought my C230 to my mechanic; his team tried myriad fixes over the last week, but was unable to solve the problem.

Any suggestions? I've done quite a bit of Googling on this issue to no avail (I've seen similar problems, but nothing quite like mine). There are a few potentially expensive solutions that may or may not work (new EIS? ignition relay? systemic fuse issue? something entirely different?). I'm curious if others have experienced this frustrating situation; I'm bringing it to the Mercedes dealership next week, but would love any theories with which you all can come up, so I can avoid expensive trial-and-error efforts from the dealer.

Thanks!

 

Thanks, Plutoe! My mechanic is Mercedes certified. Since he didn't charge me for the diagnostics he performed to try to troubleshoot the problem, he didn't want to replace the SAM or EIS if doing so wouldn't definitely fix it (as both are expensive, and the new EIS could only be used once).

Both my mechanic and I believe this issue is related to a problem with the EIS or SAM; I have an appointment with my local Mercedes dealership next week to confirm (or point toward something else). I will report back on what they find.