Chevrolet Trax: Parking assist system malfunction

Diagnostic Instructions

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

Circuit/System Description

The ultrasonic 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 sensors located in the rear bumper. The parking assist system will notify the driver using an audible signal through the radio.

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 through the audio system personalization menu.
• Hitch/Object Attached - The front and rear parking assist control module is detecting an object that is attached to the vehicle. Common items such as a hitch receiver, trailer, 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 front and rear parking assist control 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 travelling too fast in reverse at speeds of greater than 8 km/h (5 MPH).
• Inhibit - The front and rear parking assist control 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 front and rear parking assist control 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 may be missing, cut, or twisted.
• Improperly installed sensor, sensor may be crooked due to a tight wire harness.
• One or more of the sensors may be scratched or the paint may be 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 (Encore), Object Detection Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Object Detection Description and Operation (Rearvision Camera, UVC), Object Detection Description and Operation (Rear Park Assist, UD7), Object Detection Description and Operation (Side Blind Zone Alert, UFT), Object Detection Description and Operation (Rear Cross Traffic Alert, UFG)

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

Manual Transmission

1. Ignition ON, transmission in REVERSE, verify the engine control module (ECM) scan tool Reverse Position Switch parameter is Active.

• If not the specified value, refer to Backup Lamps Malfunction (Manual Transmission) , Backup Lamps Malfunction (Automatic transmission)

2. Verify the scan tool Park Assist System Status parameter displays 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.

3. If all tests normal, replace the K41 Front and Rear Parking Assist Control Module.

Automatic Transmission

1. Ignition ON, transmission in REVERSE, verify the scan tool Park Assist System Status parameter displays 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.

2. If all tests normal, replace the K41 Front and Rear Parking Assist Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for front and rear parking assist control module replacement, programming and setup

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