2008 Mercedes R-Class Owner's Manual - Page 506

Practical hints Battery ! Never loosen or detach battery terminal clamps while the engine is running or the SmartKey is in the starter switch. Otherwise the alternator and other electronic components could be severely damaged. Have the battery checked regularly by an authorized Mercedes-Benz Light Truck Center. Contact your authorized Mercedes-Benz Light Truck Center for further information. Disconnecting, removing, reinstalling and reconnecting the battery i With a disconnected battery you will no longer be able to turn the SmartKey in the starter switch and pressing the KEYLESS-GO* start/stop button will have no effect. Warning! G Step 1 (Disconnecting) Warning! G Do not place metal objects on the battery as this could result in a short circuit. Use leak-proof battery only to avoid the risk of acid burns in the event of an accident. Disconnecting, removing, reinstalling and reconnecting the battery is a complicated and technically demanding procedure that also requires safety precautions to avoid the risk of injury. We strongly recommend that it be performed by a qualified technician or an authorized Mercedes-Benz Light Truck Center only. Please read the instructions fully before beginning operation and only undertake it if you feel fully capable of performing all of the tasks involved as described in these instructions. Observe all safety instructions and precautions when handling automotive batteries ( page 503). Performing the tasks involved incorrectly can cause damage to the vehicle and impair the operating safety of the vehicle, and/or cause severe injury to you or others. i If your battery is discharged, the vehicle must be jump started ( page 511) using the jump start contacts in the engine compartment, or an accessory battery charge unit* approved by Mercedes-Benz must be connected using the jump start contacts in the engine compartment (see separate instructions for the accessory battery charge unit*) before any of the following steps can be performed. If the battery cannot be jumped or charged, please contact an authorized Mercedes-Benz Light Truck Center. Set the automatic transmission to position P ( page 192). Firmly depress the parking brake ( page 65). Turn off the engine ( page 66). Leave the ignition switched on ( page 39). 505