Mercedes SL passenger seat issue

I understand you are experiencing difficulties with the passenger seat in your Mercedes SL. I have encountered a similar issue. It is advisable to verify the condition of the battery first, as you suspected. A voltage drop can indeed cause the control module for the seat to malfunction. Furthermore, it is important to inspect the seat wiring harness, specifically the connections under the seat. Corrosion or loose connections are often the culprit. The seat adjustment motors themselves can sometimes fail, but this is less frequent than electrical supply problems.

Thanks for the quick reply! When you say seat wiring harness, are we talking about the big bundle of wires under the seat? Is there anything specific I should be looking for besides obvious breaks or corrosion? And also, what do you mean by the control module? Is that like a computer thingy for the power seats?

Yes, the seat wiring harness is the main bundle of wires connected to the seat. Carefully examine the connectors for any signs of corrosion – a white or greenish deposit. Also, gently tug on each wire to check for any that may be loose or broken inside the connector. The control module is essentially a small electronic control unit that governs the operation of the power seats. It receives signals from the seat adjustment switches and then activates the appropriate motors. Given your initial diagnosis and the symptoms, proceeding to a qualified workshop for a comprehensive diagnostic assessment would be prudent. The likely repair cost should be in the region of 290€.

Wow, thanks so much for the detailed explanation! I checked the car seats wiring as best I could, but I think you're right – this is beyond my skillset. I'll take it to my usual mechanic. At least now I have a better understanding of what's going on with the passenger seat. I'll mention the battery and control module! Thanks again!