Chevrolet Trax: DTC B0954, B0955, B0956, OR B0957: Parking assist front sensor

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.

DTC Descriptors

DTC B0954

Parking Assist Front Sensor Left Corner Circuit

DTC B0955

Parking Assist Front Sensor Left Middle Circuit

DTC B0956

Parking Assist Front Sensor Right Middle Circuit

DTC B0957

Parking Assist Front Sensor Right Corner Circuit

For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The object sensors are 3-wire sensors that are used to determine the distance between the vehicle and an object of interest. The front and rear parking assist control module supplies 8 V to the object sensors via the 8 V reference circuit and provides ground via the low reference circuit. The front and rear parking assist control module triggers the sensors in a sequential loop. After each sensor transmits, the front and rear parking assist control module uses the sensor echo received through the signal circuit to calculate the distance and position of an object.

Conditions for Running the DTC

Ignition ON

The park assist is activated. The activation takes place through putting in the reverse gear or through operating the park assist switch.

Conditions for Setting the DTC

B0954 01, B0955 01, B0956 01, or B0957 01

The front and rear parking assist control module has detected the voltage at the sensor circuit is greater than 11.5 V or the object sensor is not grounded.

B0954 06, B0955 06, B0956 06, or B0957 06

The front and rear parking assist control module has detected the voltage at the sensor circuit is less than 0.5 V.

B0954 08, B0955 08, B0956 08, or B0957 08

The front and rear parking assist control module has received an invalid signal.

B0954 21, B0955 21, B0956 21, or B0957 21

The object sensor determines no change in the position of an object while the vehicle is in motion

B0954 3A, B0955 3A, B0956 3A, or B0957 3A

The front and rear parking assist control module determines the wrong sensor type is installed.

Action Taken When the DTC Sets

• The parking assist is disabled.
• The driver information center displays SERVICE PARK ASSIST.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

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 Verification

1. Ignition ON.
2. Verify that DTC B1405 is not set.

• If the DTC is set

Refer to DTC B1405 (Rear Park Assist - UD7), DTC B1405 (Front and Rear Park Assist - UD5)

• If the DTC is not set

3. Verify that DTC B0954 01, B0955 01, B0956 01, B0957 01 B0954 21, B0955 21, B0956 21 or B0957 21 is not set.

• If the DTC is set

1. Verify the appropriate B78 Front Object Sensor is free of contamination from snow, mud, dirt, slush or ice.

• If contaminated, clean sensor.
• If there is no contamination

2. Refer to Circuit/System Testing.

• If the DTC is not set

4. Verify that DTC B0954 3A, B0955 3A, B0956 3A or B0957 3A is not set.

• If the DTC is set

Replace the B78 Front Object Sensor with the correct sensor type.

• If the DTC is not set

5. Ignition ON, transmission in REVERSE.
6. Verify the scan tool Parking Assist System Status parameter displays Enabled.

• If the Parking Assist System displays Disabled

Refer to Circuit/System Testing.

• If the Parking Assist System displays Enabled

7. All OK

Circuit/System Testing

1. Ignition OFF, scan tool disconnected, disconnect the harness at the appropriate B78 Front Object Sensor.

   It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 ohms between the low reference circuit terminal 2 and ground.

• If 10 ohms or greater

1. Ignition OFF, disconnect the harness connector X3 at the K41 Front and Rear Parking Assist Control Module.
2. Test for less than 2 ohms in the low reference circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms replace the K41 Front and Rear Parking Assist Control Module.
• If less than 10 ohms

3. Ignition ON.
4. Test for 7.5-9.5 V between the 8 V reference circuit terminal 1 and ground.

• If less than 7.5 V

1. Ignition OFF, disconnect the harness connector at the K41 Front and Rear Parking Assist Control Module.
2. Test for infinite resistance between the 8 V reference circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

  If infinite resistance

3. Test for less than 2 ohms in the 8 V reference circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K41 Front and Rear Parking Assist Control Module.
• If greater than 9.5 V

1. Ignition OFF, disconnect the harness connector at the K41 Front and Rear Parking Assist Control Module, ignition ON.
2. Test for less than 1 V between the 8 V reference circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K41 Front and Rear Parking Assist Control Module.
• If between 7.5-9.5 V

5. Ignition OFF, remove the appropriate B78 Front Object Sensor and switch locations with another properly operating sensor. Connect harness connector at both sensors. Ignition ON.
6. Verify the DTC is set for the new location in which the malfunctioning sensor is installed.

• If DTC set for the new location

Replace the malfunctioning B78 Front Object Sensor.

• If DTC set for the original location

1. Ignition OFF, disconnect the harness connector at the K41 Front and Rear Parking Assist Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V

3. Ignition OFF.
4. Test for infinite resistance between the signal circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

5. Test for less than 2 ohms in the circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K41 Front and Rear Parking Assist Control Module.
• If no DTC set

7. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Front Object Alarm Sensor Housing Replacement
• Rear Parking Assist Alarm Sensor Replacement
• Control Module References for front and rear parking assist control module replacement, programming and setup.

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