Mercedes-Benz 2010 M-Class Operator's Manual page 312

Replacing SmartKey batteries
310
i The required replacement batteries are
available at any authorized Mercedes-Benz
Center.
Replacement batteries: Lithium, type
CR 2025 or equivalent.
X
Remove the mechanical key from the
SmartKey ( Y
SmartKey
X
Press mechanical key ; into the SmartKey
opening until battery compartment
cover : opens. Do not keep the cover
shut.
X
Remove the battery compartment cover.
X
Pat the SmartKey against the palm of your
hand until battery = falls out.
X
Insert the new battery with the positive
terminal (+) facing up. Use a lint-free cloth.
X
Insert the tabs of the battery compartment
cover into the housing and press the cover
closed.
page 306).
X
Slide mechanical key : back into the
SmartKey.
X
Check the operation of the SmartKey.
SmartKey with KEYLESS-GO
X
Insert mechanical key : into opening.
X
Press mechanical key : in direction of
arrow.
Battery compartment ; is unlatched.
X
Pull battery compartment ; out of the
SmartKey housing.
X
Pull out batteries =.
X
Insert new batteries = under contact
springs ? with the positive terminal (+)
side facing up.
X
Return battery compartment ; into
SmartKey housing until it locks into place.
X
Slide mechanical key : back into the
SmartKey.
X
Check the operation of the SmartKey as
well as the KEYLESS-GO function.