When the System Does Not Seem to Work Properly

The following messages may be displayed on the DIC:

SERVICE PARK ASSIST: If this message occurs, take the vehicle to your dealer to repair the system.

PARK ASST BLOCKED SEE OWNERS MANUAL: This message can occur under the following conditions:
• The ultrasonic sensors are not clean. Keep the vehicle's rear bumper free of mud, dirt, snow, ice, and slush. For cleaning instructions, see Exterior Care on page 10‑86.
• The park assist sensors are covered by frost or ice. Frost or ice can form around and behind the sensors and may not always be seen; this can occur after washing the vehicle in cold weather. The message may not clear until the frost or ice has melted.
• A trailer was attached to the vehicle, or an object was hanging out of the liftgate during the last drive cycle. Once the object is removed, URPA will return to normal operation.
• A tow bar is attached to the vehicle.
• The bumper is damaged.
Take the vehicle to your dealer to repair the system.
• Other conditions, such as vibrations from a jackhammer or the compression of air brakes on a very large truck, are affecting system performance.

    See also:

    Cooling System
    If the vehicle has the Duramax® Diesel engine, see the Duramax® Diesel Supplement for more information. The cooling system allows the engine to maintain the correct working temperature. 5.3 L En ...

    Engine Identification
    The eighth character in the VIN is the engine code. This code identifies the vehicle's engine, specifications, and replacement parts. See “Engine Specifications” under Capacities and Speci ...

    Antilock Brake System (ABS)
    This vehicle has the Antilock Brake System (ABS), an advanced electronic braking system that helps prevent a braking skid. When the engine is started and the vehicle begins to drive away, ABS checks ...