Parking Assist System Malfunction

Parking Assist System Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.

Circuit/System Description

The parking assist system is designed to identify and notify the driver of an object in the vehicle's path when reversing at speeds of less than 8 km/h (5 mph). The distance and location of the object is determined by four object alarm sensors located in the rear bumper. The parking assist system will notify the driver using an audible signal through the radio speakers.

Diagnostic Aids

When the "Park Assist Off", "Park Asst Blocked See Owners Manual", or "Park Assist Blocked See Owners Manual" message is displayed in the DIC the disable reason is stored in the Park Assist Disable History.

The scan tool Park Assist Disable History parameters are a list of the seven previous reasons the parking 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 parking assist system has been disabled by the vehicle operator using the parking assist disable switch.
* 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.

Reference Information
Schematic Reference

Object Detection Schematics [1][2]Collision Avoidance and Parking Assist Systems
Connector End View Reference

Component Connector End Views Connector End Views By Name
Description and Operation

Object Detection Description and Operation
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearningfor scan tool information

Circuit/System Verification

1. Ignition ON, verify the parking assist system is enabled through the DIC.

• If the parking assist system is manually disabled, enable the system. Refer to the vehicle owners manual for instructions on enabling the system.

2. Observe the scan tool Park Assist Switch parameter while pressing and releasing the park assist disable switch. The parameter should change between Active and Inactive.

• If the parameter does not cycle between the specified values, refer to Park Assist Disable Switch Circuit Malfunction.

3. Observe the scan tool Park Assist Switch LED parameter while pressing and releasing the park assist disable switch. The parameter should change between On and Off.

• If the parameter does not cycle between the specified values, refer to Park Assist Disable LED Circuit Malfunction.

4. Transmission in REVERSE, verify one audible beep sounds and the scan tool Park Assist System Status parameter is Enable.
Note: After completing the next step the vehicle might need to be driven in the forward direction at speed greater than 40 km/h (25 mph).

• If not the specified values, refer to Diagnostic Aids and the scan tool Park Assist Disable History parameters to determine the cause of the inhibit.

Circuit/System Testing

Park Assist Disable Switch Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the I/P multifunction switch.
2. Test for less than 10 Ohms between the appropriate ground circuit terminal listed below and ground.

* X88/Z88 terminal 3
* Z75 terminal 5

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Park Assist Switch parameter is Inactive.

• If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the object alarm module.

4. Install a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Park Assist Switch parameter is Active.

• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the object alarm module.

5. If all circuits test normal, test or replace the I/P multifunction switch.

Park Assist Disable LED Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the I/P multifunction switch.
2. Ignition ON, verify a test lamp illuminates between the appropriate ignition circuit terminal listed below and ground.

* X88/Z88 terminal 6
* Z75 terminal 4

• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect the harness connector at the I/P multifunction switch. Disconnect the X1 harness connector at the object alarm module.
4. Ignition ON, verify the park assist disable LED is not illuminate.

• If the LED is illuminated, test the control circuit for a short to ground. If the circuit tests normal, test or replace the I/P multifunction switch.

5. Install a 10A fused jumper wire between the control circuit terminal 3 and ground. Verify the park assist disable LED is illuminated.

• If the LED is not illuminated, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the I/P multifunction switch.

6. If all circuits test normal, replace the object alarm module.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Accessory Switch Replacement
* Control Module References Programming and Relearningfor object alarm module replacement, programming and setup