Mercedes-Benz Air Suspension Control Module Replacement

Symptoms

This module was replaced because it was displaying a fault code for a faulty air strut ADS valve. The suspension was stuck in SPORT mode, and the ride quality was very rough. 

Even after replacing the "faulty" strut, the code was still showing current in the airmatic control module. Wires from air strut to airmatic module were tested.

Replacing the airmatic module itself fixed the problem. 

What you will need

Parts

• Mercedes Airmatic control unit
• Used modules can be installed but ensure that you are using the correct part number.

Tools

• 10mm socket
• Ratchet wrench

Procedure 

Follow these steps to replace the airmatic control unit on a Mercedes Benz S-Class W221.

Removal

1. Disconnect the negative terminal on the battery. The battery on W221 is located behind the rear seat and can be accessed via the trunk. 
2. Locate the airmatic control module in the passenger footwell.
3. Grab one side of the carpet and pull it towards you, and push the carpet down.

    

4. Remove the 10mm plastic nuts of the module frame, and pull down the metal plate.

    

5. Using a 10mm socket remove the bolts on the metal bracket that is holding the control module.

    

6. To disconnect the connectors from the control module, you have to pull the connector lock and separate the connectors.

Installation:

1.  Align the connectors to the control module and push the tab to lock.

    

2. Install the metal bracket and tighten the bolts.

    

3. Return the metal plate, and tighten the plastic nuts.

    

4. Install the scanner and program the module.

Even though the module functioned properly without any programming, it is recommended to transfer the coding from the old control unit when possible. 

Notes:

• Make sure to disconnect the negative terminal of the battery every time you are performing a module replacement.
• Make sure to scan the vehicle before performing the module replacement to have an idea about what codes are already in store before replacing the module and what occurred after replacing the module.
• Back up the coding of the airmatic control module and restore it to the unit.