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Recently purchased a 2013 c300 sport. I've noticed that not all the doors lock. The 2 rear doors always lock, the front doors sometimes they both lock other times only 1 will lock. This happens when using both the key fob, or when trying to lock the door from inside the car. Car was sitting for a few months had a bunch of fault codes due to the battery be dead that have not come back on after being cleared. The only ones that keep coming back are for the front 2 doors lock motor output faults. My question is could this be related the the batteries in the car being the original batteries from 2013 ? Does the auxiliary battery supply power to the door lock due to it being old doesn't provide enough power to the modules when the car is off ? Any help would be great thanks
You have two batteries in the car? Have you replaced the batteries with new batteries? Is that what the manufacture dates on the batteries show, that they are original from 2012-13?
I would think if there were an issue with the aux battery then it would show as a fault or notification on the dash, a red battery warning would show followed by some type of message for service. Im just guessing.
With the key in the ignition and the car turned on, engine not started, how else does everything operate like the radio and the exterior lights, moving the seats? if everything is fine then I would say the batteries are fine.
If the only issue is with the two front doors then I would say its an issue with the two front doors.
Does it have the issue with three car running also? If not utt could be the battery but I'm guessing they don't work with the car running either so imma say use a doir lock problem then and not the battery.
The battery in the trunk I believe is only to keep power and settings when the engine shuts off if you have eco mode on and come to a stop.
You have two batteries in the car? Have you replaced the batteries with new batteries? Is that what the manufacture dates on the batteries show, that they are original from 2012-13?
I would think if there were an issue with the aux battery then it would show as a fault or notification on the dash, a red battery warning would show followed by some type of message for service. Im just guessing.
With the key in the ignition and the car turned on, engine not started, how else does everything operate like the radio and the exterior lights, moving the seats? if everything is fine then I would say the batteries are fine.
If the only issue is with the two front doors then I would say its an issue with the two front doors.
Yes the battery is dates 50 12 on the post
so I'm assuming it's the 50th week of 2012
I am very impressed seeing a 12yr old battery sill working and makes me feel good about my choice to replace my battery with the same MB battery. I replaced my battery 2yrs ago and that one was 7yrs old.
You mention the doors not locking sometimes, what about unlocking? What happens if you go out to the car and just keep pressing unlock/lock on the key fob?
Mine locks all the doors automatically when I put the car in drive, I may have to start moving or get to a certain speed I dont remember. The setting is somewhere in the settings menu using the steering wheel buttons.
I'm going to change both batteries today. Everything seems to work when the car has been running for 10-15 minutes. I'm guessing after running a while the alternator is charging the system and providing power to wake up the modules to send signals. And then when the car shuts off the old battery is not providing enough voltage to keep everything communicating. The voltage of the battery when the car is off is reading 11.7
It's also happening to mine.
W204 2009.
The two rear doors ain't locking or unlocking, I checked the wires that trigger the actuator and there isn't any current received when I use the key fob to central lock.
I'll suggest you check the wires, fuse box or actuator
I changed the batteries, no luck with getting the door lock to work properly rear doors work every time, but front doors still only work now and then.
I was able to get a scanner today to read the fault codes says central lock output has malfunction really have no idea what to do next
Last edited by Dougjoyce00; Dec 10, 2024 at 11:03 PM.
Here's what I'll suggest 🤔, check if the door module has corrosion or moist, clean it up and fix it back.
Cus, there's actually no fault in the front or rear sam
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