Hi all, new forum member here. My husband has a 2006 CLK-350 which has developed a very strange disease, and I am hoping someone here will recognize the symptoms.

The first time it happened, we were driving down the freeway and the radio turned itself off. We turned it back on and all was fine. But a few minutes later the windows started to fog up and we realized the climate control was off. And a few minutes after that, the entire control panel, speedometer and such, went off. We pulled into a rest stop and he stopped and restarted the car, which brought everything back to life.

The next time it happened we were almost to our destination so he kept going; more and more things stopped working until finally the engine died, fortunately while we were in the parking lot. Once again, restarting the car fixed everything.

At this point he took it to the Mercedes dealer that does his regular service. They spent hours working on it but could not figure out what was going on; there were many codes being thrown but they couldn't determine which one represented the cause.

After getting it back he continued to drive it. Some days it would be just fine. Other days the climate control would keep going off, and he would have to keep stopping and restarting before the rot spread. Until the day he called me to come get him, because he had pulled over to restart and the car would not start....

He has an electronic key fob, and there was now a red blinking light on the key, a new development. I brought him the spare fob and with this he was able to start the car again. It has mostly sat in our garage since then while we figure out what to do next.

It's possible that the fob is failing and has done damage to the car's electronics. It's also possible that the car's electronics are failing and have done damage to the fob. Or that the two are unrelated issues.

Does this ring a bell with anyone? He already spent hundreds of dollars at the dealer with no resolution, and he has been told that the replacement fobs are obscenely expensive, so he doesn't really want to go back again without some idea of what might be wrong to help them focus their efforts.

Thanks in advance!

 

Does this primarily happen in wet weather?

Is there any possibility mice may have made their home in the wiring? This usually happens when the car sits unused for extended periods.

My first bet would be a failing ignition switch. Alternately it could be an EDU issue.

 

The first time it happened was September 20th, and IIRC it was still dry here. Since then it has been damp pretty much all the time, but the night the engine conked out and the night it wouldn't start were both dry insofar as no rain was actually falling. The roads are nearly always damp this time of year so there's always a bit of water around.

The car is garaged and driven regularly, and I've never seen any mice about, so I don't think so. Also I would hope that the dealer would have noticed something as obvious as a chewed wire, though I do realize that's stretching things a bit.

An ignition issue seems possible, though I don't know why it would start with one key and not the other? And would that cause the "rot" that sets in as things stop working while going down the road?

I don't know what an EDU is - I tried Google but it assumes I mean education and goes down a different rabbit hole.

Thanks!

 

Sorry, typo, I meant ECU, the Electronic Control Unit.

I am not sure about Mercedes, but on Porsches a bad ignition switch can cause exactly the kind of bizarre shutdowns you are experiencing. Especially when shutting the car down and restarting it can get you going again.

Another possible cause that you absolutely should check out is a bad car battery. Low battery voltage can cause similar bizarre problems. Check the battery voltage when the car is off and when its running. If the battery is low, try replacing it. If it goes low again, check the alternator and voltage regulator.

I would start with the battery voltage, if that doesn't work the ignition switch and finally the ECU. Hope you are lucky and discover its the battery.

Anker

 

Yes, this could be a bad EIS (electronic ignition switch). I have also heard of a bad key causing this. Check the inside of the key to make sure it's not clogged with pocket lint, and that there are no obvious burnt/broken solders on its circuit board. The circuit board can be pulled out by (gently) using tweezers or pliers on it after you remove the battery tray.

 

These shut down if battery is to low . Under low voltage it will shut off the engine ecu Keep the battery well charged and see if it goes again..Worth a try for free.

 

I don't believe the instrument cluster would shut off due to low voltage. Only the "auxiliary consumers" are shut down for low voltage - vario roof, heated/vented seats, etc.

EDIT: Oops, sorry, ignore that above - I was thinking of the R230 with the two battery system. Yes, low voltage can cause all sort of electrical gremlins. Start there: 12.6v at rest, 11v during cranking, 14v at idle. More than 0.1 volts lower than that and I'd start looking at what is wrong - bad battery, alternator, or something draining the battery overnight.

 

hope it isnt your EIS, charge up the cars battery and see if that helps anything

 

Just a followup - he has been driving the car using the "spare" key and it hasn't done anything out of the ordinary, so it looks like it was the main key fob that was to blame. Thanks everyone for your help!

 

Thanks for the reply .Just enjoy now ..