61 20 908 Performing battery "power reset" (for programming/coding control unit(s))

The Following Steps Must Be Carried Out For A "Power Reset": 

• Switch off and disconnect battery charger.
• Switch off ignition.

  Cars with ignition key:  Turn ignition key to 0 position.

  Cars with identification sensor  : Remove identification sensor from slot.

  Cars with comfort access system:  Make sure terminal is in 0 position.

• Disconnect battery negative terminal.
• Reconnect battery negative terminal (to ensure bus activity).
• Waiting time (5-10 seconds).
• Disconnect battery negative terminal.
• Waiting time (1 minute).
• Connect battery negative terminal and tighten, tightening torque, refer to 61 21 1AZ in GENERAL ELECTRICAL SYSTEM - TIGHTENING TORQUE - E60 .
• Connect and switch on battery charger.
• Switch ignition on.