If you’re experiencing issues with your Mercedes Benz W221 lumbar support, and suspect it might be related to software or coding, this guide is for you. Often, the lumbar support system’s functionality can be tied to the correct coding within your vehicle’s seat control unit. This article will walk you through the process of checking and adjusting the lumbar support settings using a diagnostic tool like STAR or DAS.
The initial question pointed to the lumbar support control module N32/N24, located in the middle of the backrest, accessible by removing the seat back. However, before diving into hardware, it’s crucial to verify the software configuration. Sometimes, after a software update or in cases of incorrect initial setup, the lumbar support feature might be deactivated in the system’s coding.
To check and potentially rectify this, you’ll need to access the version coding menu through your diagnostic tool. Here’s how you can navigate to the relevant settings:
-
Connect to your Vehicle: Begin by connecting your Mercedes Benz W221 to the STAR or DAS diagnostic system. Enter your Vehicle Identification Number (VIN) to establish communication with your car’s systems.
-
Navigate to Control Units: Once connected, proceed to the “Control units” menu. This section allows you to access and manage various electronic control units within your vehicle. There’s no need to run a quick test at this stage, go directly to control unit selection.
-
Access Seats and Doors Menu: Within the “Control units” menu, locate and select the “Seats and doors” menu. This is where you’ll find the control modules related to seat functions.
-
Select Seat Control Unit: Depending on whether you are addressing the driver’s side or passenger side seat, choose either “ESA-FR” (Front Right Seat – Passenger Side) or “ESA-FL” (Front Left Seat – Driver Side).
-
Enter Control Unit Adaptations: After selecting the appropriate seat control unit, proceed to “Control unit adaptations”. This menu contains options for customizing and configuring the control unit’s parameters.
-
Access Version Coding: Within “Control unit adaptations”, select “Read coding and change if necessary”. This will display the current coding settings for the seat control unit, allowing you to make adjustments.
-
Check Lumbar Support Adjustment Setting: Scroll through the list of coding options until you find “Lumbar support adjustment”. Examine the current setting. If it is set to “NOT PRESENT”, this could be the reason why your lumbar support is not functioning or why you are missing the actuation menu in your diagnostic tool.
-
Change Lumbar Support Setting to PRESENT: If the “Lumbar support adjustment” setting is “NOT PRESENT”, change it to “PRESENT”. This will activate the lumbar support feature within the software configuration.
-
Verify Pneumatic Pump Setting: Look for another setting, usually related to the pump. It might be labeled “Pneumatic pump for lumbar support adjustment”. Ensure this setting is configured to “Lumbar support adjustment with series pump”. This setting ensures that the system recognizes and utilizes the correct pneumatic pump for the lumbar support function.
-
Test Actuation: After making these coding changes, navigate to the “Actuations” menu within the seat control unit diagnostics. You should now find the “Lumbar support adjustment” selection available. Use this menu to test the lumbar support adjustments and confirm if they are now working as expected.
It’s important to understand why these settings might be incorrect in the first place. While it’s less common for these settings to change spontaneously, a software update could potentially reset or alter coding parameters. If the lumbar support was incorrectly coded as “NOT PRESENT”, it would explain the absence of fault codes even when the control unit is disconnected, as the system wouldn’t be expecting or monitoring this feature.
By following these steps to check and correct the lumbar support coding, you can often resolve issues related to its functionality on your Mercedes Benz W221. If the problem persists after verifying and correcting the coding, further diagnosis of the pneumatic pump, control module N32/N24, or wiring might be necessary.
