GM Service Manual Online
For 1990-2009 cars only

The park assist system is capable of performing an object detection sensor self test. While in the sensor self test mode the park assist module will verify inputs from the object detection sensors. The park assist module indicates sensor status using the system alarm. If all sensor signals are being received by the rear park assist module 1 single short tone will be activated. When 1, 2 or all 3 sensor signals are not received the module will respond by activating the alarm with 1 tone repeated for a left sensor fault, 2 tones repeated for a center sensor fault and 3 tones repeated for a right sensor fault. If all sensors are faulted the module will respond by activating the alarm with 1 tone repeated 3 times then 2 tones repeated 3 times and 3 tones repeated 3 times then repeat the sequence.

To enter the object sensor self test complete the following steps:

  1. Turn the ignition ON.
  2. Apply and release the parking brake 3 times within 10 seconds after the ignition is turned ON.
  3. The system will be in the object sensor self test mode.
  4. To exit the object detection sensor self test mode turn the ignition OFF.