GMC 2007 Acadia Owner's Manual page 510

Ignition Transmission Lock Check
While parked, and with the parking brake set,
try to turn the ignition to OFF in each shift lever
position.
•
The ignition should turn to OFF only when the
shift lever is in PARK (P).
•
The ignition key should come out only in OFF.
Contact your dealer/retailer if service is required.
Parking Brake and Automatic
Transmission Park (P) Mechanism Check
CAUTION:
{
When you are doing this check, your
vehicle could begin to move. You or
others could be injured and property
could be damaged. Make sure there is
room in front of your vehicle in case it
begins to roll. Be ready to apply the
regular brake at once should the vehicle
begin to move.
510
Park on a fairly steep hill, with the vehicle facing
downhill. Keeping your foot on the regular
brake, set the parking brake.
•
To check the parking brake's holding ability:
With the engine running and the transmission in
NEUTRAL (N), slowly remove foot pressure
from the regular brake pedal. Do this until the
vehicle is held by the parking brake only.
•
To check the PARK (P) mechanism's holding
ability: With the engine running, shift to
PARK (P). Then release the parking brake
followed by the regular brake.
Contact your dealer/retailer if service is required.
Underbody Flushing Service
At least every spring, use plain water to flush
any corrosive materials from the underbody.
Take care to clean thoroughly any areas where
mud and other debris can collect.