Chevrolet Impala Owner's Manual page 304

Allowing the wiper arm to touch
the windshield when no wiper
blade is installed could damage
the windshield. Any damage that
occurs would not be covered by
your warranty. Do not allow the
wiper arm to touch the windshield.
To replace the wiper blade:
1. Pull the wiper assembly away
from the windshield.
2. Lift up on the latch in the middle
of the wiper blade where the
wiper arm attaches.
3. With the latch open, pull the
wiper blade down toward the
windshield far enough to release
it from the J-hooked end of the
wiper arm.
4. Remove the wiper blade.
5. Reverse Steps 1 3 for wiper
blade replacement.
Headlamp aim has been preset and
should need no further adjustment.
If the vehicle is damaged in a crash,
the headlamp aim may be affected.
If adjustment to the headlamps is
necessary, see your dealer.