Transfer Case Control Module Installation Details (N15/7)
1. On models with the corresponding configuration (code ET2), activate the service mode of the TELE AID emergency call system (see Section Activation/deactivation of the service mode of the TELE AID emergency call system).
2. Disconnect the negative cable from the battery.
3. Remove the center console (see Chapter Body).
4. Remove the rear Signal Activation and Sensing Module (SAM)/Fuse and Relay Box.
[Information copied from the website: MercedesMAN]
5. Disconnect the electrical wiring, loosen the four mounting nuts and remove the transfer case control module (N15/7).
6. Installation is carried out in reverse order.
7. Finally, do not forget to deactivate the service mode of the TELE AID system (with appropriate equipment) and clear the memory of the on-board diagnostic system processor.