Mercedes-Benz S-Class Saloon W223 2021 Owner's Manual page 385

Observe the additional following points during
starting assistance:
Starting assistance may only be provided
R
using vehicles, batteries or other jump start
devices with a nominal voltage of 12 V.
The vehicles must not touch.
R
Vehicles with a petrol engine: jump-start the
R
vehicle only when the engine and exhaust sys-
tem are cold.
Starting assistance and charging the 12 V battery
Preparing for starting assistance/the charging
process
Secure the vehicle by applying the electric
#
parking brake.
Select transmission position j.
#
Switch off the ignition and all electrical con-
#
sumers.
Open the bonnet.
#
Open cover 1.
#
Slide protective cover 2 of positive contact
#
3 on the jump-start connection point in the
direction of the arrow.
P223 0288 02
Breakdown assistance 383
Starting assistance
Connect the positive contacts of the vehicles
#
with the jump lead. Start with your own vehi-
cle first.
Start the engine of the donor vehicle and run
#
it at idling speed.
Connect negative terminal 4
#
battery to the earth point of your vehicle using
of the donor