What is the reason for the failure of one side of the Mercedes-Benz power seat?
3 Answers
The reasons for the failure of one side of the Mercedes-Benz power seat are: 1. The power seat is stuck or jammed, mostly due to oxidation or insufficient lubrication of the seat adjustment linkage; 2. Electrical issues, check if there is a problem with the fuse, and then inspect whether the seat motor is functioning properly. Power seat adjustment allows for the control of the seat's forward and backward position, height, and backrest angle through the motor. Taking the Mercedes-Benz C-Class 2021 C200L Dynamic Sport Edition as an example: its length, width, and height are 4784mm, 1810mm, and 1457mm respectively, with a wheelbase of 2920mm, a top speed of 221 kilometers per hour, and equipped with a 9-speed automatic manual transmission.
I just encountered this issue last week. The backrest adjustment on the driver's seat of my Mercedes-Benz malfunctioned—it could tilt to the left but not the right. After struggling for a while, I found that the wiring connector under the seat had come loose, probably due to water splashing in during car washing causing poor contact. I removed the seat base panel, dried the connector with a hairdryer, and plugged it back in tightly, and it worked fine again. This kind of problem is quite common, especially in older cars with aging wiring or when kids kick the wiring harness in the back seat. I recommend first checking if any snacks are stuck under the seat blocking the switch, then using a multimeter to test the motor voltage. If the motor doesn't respond, chances are the switch module is faulty—replacing it with an original part could cost two to three thousand. Regularly cleaning the seat rails can help prevent such failures.
There are essentially three reasons for a malfunctioning Mercedes power seat on one side: either the motor is dead, the control switch has poor contact, or the wiring is broken. The funniest case I've seen while repairing cars was a coin stuck in the slide rail causing motor overload and burnout. Focus on checking the memory button group on the side of the seat—that octopus switch is prone to water ingress and oxidation. If you hear the motor humming but it doesn't move during adjustment, it's likely a gear jam or slide rail deformation. In older Mercedes models, the seat control module is under the right rear floor mat, and water ingress can cause it to send erratic commands. If you're attempting a DIY fix, disconnect the battery negative terminal for ten minutes to reset the system. If that doesn’t work, you’ll have to take it to a shop to read the fault codes. Never force the seat to move, as breaking the steel cable would make the problem even worse.
