Diagnostic Aids

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The scan tool Park Assist Disable History parameters are a list of the seven previous reasons the park assist system was disabled. These parameters may help in the diagnosis of an intermittent concern or a customer concern which is the result of normal system operation. The following is a brief description of potential causes which may aid in diagnosis:

Manual Disable - The park assist system has been disabled by the vehicle operator using the parking assist disable switch.
Park Brake - The vehicle parking brake is applied or a malfunction exists within the parking brake system.
Hitch/Object Attached - The object alarm module is detecting an object that is attached to the vehicle or the endgate is lowered, if applicable. Common items such as a hitch receiver, trailer, object hanging out of endgate, or a bicycle rack may cause this concern. Additionally, damage to the rear of the vehicle or a misaligned sensor may cause this concern. If the vehicle is damaged in a manner that causes the sensor to detect the bumper itself, the object alarm module will interpret this as an attached object and disable the system. Carefully inspect the bumper, bumper mounting surface, and sensor retainers before continuing with normal diagnosis. After the detected cause has been addressed the vehicle must be driven at speed greater than 40 km/h (25 mph).
Reverse Overspeed - The vehicle is traveling too fast in reverse at speeds of greater than 8 km/h (5 mph).
Inhibit - The object alarm module has lost or received invalid GMLAN signal(s).
Sensor Disturbance - An outside interference is causing sensor movement. Such interference may be caused by a heavy pounding, like that of a nearby jackhammer, or large changes in pressure, such as a large truck's air brakes.
Sensor Ring Time - If the sensor fails its own diagnostic initialization the object alarm module will set this error. After the detected cause has been addressed the vehicle must be driven at speed greater than 40 km/h (25 mph). The following is a list of reasons this cause may have set:
- One or more of the sensors may be blocked by snow, mud, ice, or other debris. This might happen after going through a car wash in cold weather.

- Silicone insulator surrounding sensor maybe missing, cut, or twisted.

- Improperly installed sensor, sensor maybe be crooked due to a tight wire harness.

- One or more of the sensors may be scratched or the paint maybe chipped.

- Excessive paint thickness on a sensor may cause an excessive sensor ring time. When replacing or refinishing a sensor, do not apply an excessive amount of paint or clear coat.