Please forgive me if I'm not in the right place. My central locking system had been working just fine on my 1998 C230 until a few hours ago. I was out and about, 3 times this morning, with no problems locking and unlocking my doors with my remote. I then decided to use my remote to unlock my doors so that I could vacuum the car interior (I was going to go to the car wash later so the car has not been washed in a week). I remember hitting the clock's hour button, by accident, but that's all. When I was finished vacuuming I grabbed my remote to lock the doors and they wouldn't lock.

The remote is fine as it lights up. I attempted to reset the remote with no luck. When I hit the lock button, the exterior lights blink 3 times but doors won't lock. However, if I open the car door, the alarm will go off and if I hit the unlock button, on the remote, the alarm will turn off. All interior and dash lights work. The windows and mirrors work but I am unable to unlock the trunk from the console trunk release on the dash console or by the metal key that slides out of the remote. Oddly enough, I just noticed that not only is the red alarm light blinking on the dash, but there's also a red light blinking on the central locking button on the dash console. That was not blinking earlier. I want to believe I must have done something to knock everything out of sync but I truly don't know what. It also seems odd that the locking system would go out suddenly without warning. I don't know how to check the fuses since I can't get into the trunk. Is there anybody out there that may know what I've done or what I could try? My apologies for such a long post but I wanted to give as much information as possible. Thank you so much for your help.

UPDATE: I thought I'd try the remote to lock the doors just one last time and it worked! I locked and unlocked three times and things seem ok. Maybe the motor is going bad or maybe it just needed time to re-sync. If anyone has any ideas as to why it's suddenly working again, please let me know. Many thanks!

 

One thing that is always good to do if it has not been done in awhile is replace your battery in your key fob. Also these models are known for having the vacuum pump go bad, which controls the locking system.

 

Thank you so much. I think I will replace the key fob battery just in case.

Mercedes said my passenger door actuator was bad and replaced it. The doors worked, with the remote, until the next morning when I was leaving for work. The remote didn't work and I once again couldn't open the doors but with the valet key. Called Mercedes back, took the car back in, and now they claim the vacuum pump is bad. The doors lock and unlock, with the remote, intermittently. Some days the remote will lock and unlock all day and other days it won't work at all. And now Mercedes wants $798, for the pump, excluding labor.

I'm just wondering why they wouldn't have originally checked to see if the pump was bad! Is it possible the vacuum pump truly is bad even though it works some days? Thank you!

 

Just had my vacuum pump fail, exactly same symptons as you describe. When you replace it check the system for leaks. Mine failed because of a leak and ran full time!

 

Ok so I am new to the Merc world. I just bought a 97 which is slightly differnt. From what I can tell the module that runs the pump and the locks is in the passenger footwell. I had the issue of rain water or car wash water filling up the windshield drain and spilling into the cabin. I noticed my locks would not work when it rained or i washed the car. I have since fixed the drain problem and have had no issues with the lock system.

 

I got a pump for sale.