Experiencing issues with your W221 Mercedes-benz lumbar support system? Specifically, are you unable to find the lumbar support actuation test within your DAS/Xentry diagnostic system, even after a software update? This guide is for W221 Mercedes-Benz owners and technicians who are facing this frustrating problem. We will walk you through how to check and potentially correct the coding for your lumbar support system to regain access to these diagnostic features.
It’s often assumed that the version coding for your lumbar support should be correctly configured from the factory. However, software updates or unforeseen issues can sometimes lead to incorrect settings. Before diving into more complex troubleshooting, verifying the coding is a crucial first step. This guide focuses on accessing the relevant menus in DAS/Xentry to confirm and, if necessary, adjust the lumbar support coding.
To begin, connect your Mercedes-Benz W221 to your STAR diagnostic system and enter the vehicle identification number (VIN). Once you’ve established communication with the car, follow these steps to navigate to the version coding menu:
Accessing Version Coding for Seat Control Units
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Navigate to Control Units: After the system has identified your vehicle, proceed to the “Control units” menu. This is typically found in the main selection screen after VIN entry. There’s no need to run a quick test beforehand for this procedure.
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Select “Seats and Doors” Menu: Within the “Control units” menu, locate and select the “Seats and doors” category. This section contains the control modules related to seat functions, including lumbar support.
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Choose the Relevant Seat Control Unit: Depending on whether you are working on the driver’s side or passenger’s side seat, select either “ESA-FR” (Electric Seat Adjustment – Front Right) or “ESA-FL” (Electric Seat Adjustment – Front Left). These modules control the various seat adjustments, including lumbar support.
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Enter “Control unit adaptations”: Once you’ve selected the appropriate seat control unit (ESA-FR or ESA-FL), proceed to “Control unit adaptations”. This menu allows you to modify the settings and configurations of the selected control unit.
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Select “Read coding and change if necessary”: Within the “Control unit adaptations” menu, choose the option labeled “Read coding and change if necessary”. This will allow you to view the current coding settings and make adjustments if needed.
Checking and Correcting Lumbar Support Coding
After accessing the coding menu, you will see a list of various configurable parameters. Look for the following settings related to lumbar support:
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“Lumbar support adjustment”: This is a critical setting that determines whether the system recognizes and enables the lumbar support function. It’s often the fourth entry on the list. Check the current setting.
- If the setting is “NOT PRESENT”: This could be the reason you are missing the lumbar support actuation test in DAS/Xentry. Change the setting to “PRESENT”. This will inform the system that lumbar support is installed and should be active.
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“Pneumatic pump for lumbar support adjustment”: This setting specifies the type of lumbar support system being used. It should be configured to match your vehicle’s equipment.
- Verify the setting: Ensure this setting is set to “Lumbar support adjustment with series pump”. This is the standard configuration for W221 Mercedes-Benz models equipped with lumbar support.
After making these coding adjustments, it is advisable to exit the menus and then re-enter the “Actuations” menu within the seat control unit diagnostics. Now, navigate to the “Lumbar support adjustment” selection. You should now find the actuation tests available, allowing you to test the functionality of the lumbar support system and confirm if the coding changes have resolved the issue.
Further Considerations and Potential Causes
If the lumbar support was indeed coded as “NOT PRESENT,” it raises questions about how this setting might have changed. It’s less likely for these settings to change spontaneously unless:
- Software Update Issues: As mentioned in the original query, a recent software update could potentially have introduced a bug or inadvertently reset coding parameters.
- Previous Diagnostic or Coding Errors: If the vehicle has been previously diagnosed or coded, there’s a possibility of unintentional changes to the lumbar support settings.
It’s also worth noting that if the lumbar support was incorrectly coded as “not present,” it could explain the absence of fault codes even when the lumbar support control unit (module N32/N24, located in the seat backrest) is unplugged. The system might simply not be expecting or monitoring a feature that is coded as non-existent.
By verifying and correcting the lumbar support coding in your W221 Mercedes-Benz, you can often restore the functionality of your lumbar support system and regain access to valuable diagnostic tools within DAS/Xentry. This step-by-step guide provides a clear pathway to troubleshoot this specific issue and ensures your seat control units are correctly configured for optimal performance.
