333 Operation
Driving instructions
Extreme care must be exercised since 
your vehicle with a trailer will require 
additional passing distance ahead than 
when driving without a trailer.
Because your vehicle and trailer is 
longer than your vehicle alone, you will 
also need to go much farther ahead of 
the passed vehicle before you can re-
turn to your lane.
Uncoupling the trailer
Make sure the automatic transmission 
is set toP (
page 185).
Set the parking brake for the vehicle 
(
page 65).
Start the engine (page 54).
Close all doors and the tailgate.
Set the parking brake for the trailer.
Disconnect all electrical plug connec-
tors.
Uncouple the trailer.
Make sure that the trailer coupling is 
free of load.
Turn off the engine (page 66).
Warning!G
Vehicles with air suspension program*:
While you are coupling or decoupling a trail-
er, make sure that you do not
lock or unlock
open or close
a vehicle door or the tailgate.
The vehicle’s level could change and you 
could endanger yourself and/or others as a 
result.
Make sure that you do not operate the ADS 
button* (
page 255) or the vehicle level 
control system* (
page 255) when cou-
pling/decoupling the trailer.
Warning!G
Vehicles with air suspension program*:
As soon as you disconnect the electrical 
connection between the trailer and the 
vehicle, the vehicle will lower. To help avoid 
personal injury, make sure no one is near 
the wheel housing or underneath the vehicle 
before the electrical connection is discon-
nected.
When you uncouple the trailer, the vehicle is 
temporarily raised because the springs are 
relieved of load. Be especially careful during 
this process, as you could otherwise injure 
yourself and/or others. Make sure that any 
persons remaining in the vehicle do not 
press the switches for vehicle level control 
or the ADS*. 
462 Practical hints
Replacing SmartKey batteries
3Batteries
4Contact spring
Pull out batteries3.
Using a line-free cloth, insert new 
batteries3 under contact springs4 
with the positive terminal (+) side 
facing up.
Return battery compartment2 into 
housing until it locks into place.
Slide mechanical key1 back into the 
SmartKey or SmartKey with 
KEYLESS-GO*.
Check the operation of the SmartKey 
or SmartKey with KEYLESS-GO*.