Mercedes-Benz W211 battery replacement and precautions
How do I replace the W211 battery without damaging the electronics?
Drive the car into the garage, take the key out of the ignition and switch off the consumers. Wait before disconnecting the terminals so that the car's systems and bus have time to go to sleep; in instructions the time varies from a few minutes to half an hour. Opening a door or pressing the brake wakes the car up again.
In what order are the battery terminals disconnected and connected?
Disconnect the negative terminal first and then the positive terminal. Connect the positive terminal first and the negative terminal last. The terminals must not be swapped. A wrongly done disconnection can damage the SAM control unit at the rear, causing faults in the instrument cluster and in several functions.
What has to be done after replacing the battery?
Radio or navigation codes are not needed. The power windows, sunroof and steering angle sensor have to be reinitialised, and the clock and the mirror folding are set again. If fault codes accumulate, they can be read and cleared with a fault code reader; if they return, have the car checked at a workshop.