Mercedes-Benz 2013 M Class - Manual (Page 351)

Using the 115 V power socket
X To switch on: switch the ignition on.
X Open flap =.
X Insert the plug of the electronic device into
115 V power socket :.
Indicator lamp ; lights up.
X To turn off: disconnect the plug from
115 V power socket :.
Ensure that you do not pull on the cord.
Features
349
Stowage and features
Z