Chevrolet Trax: Side object 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.

Diagnostic Fault Information

Circuit/System Description

The side object sensor modules are located on each side of the vehicle behind the rear fascia and are not directly visible from outside the vehicle. The sensors use radar to determine the presence of objects nearby. The left side object sensor is the master that communicates on serial data. There is a private communication network between the left and right sensors. The scan tool can communicate only with the left sensor.

Side blind zone alert is active when the vehicle is out of park or the parking brake is off on manual transmission vehicles. If a vehicle is detected in the side blind zone, the warning symbols will turn illuminate on the appropriate side. The warning symbols will vary brightness based on the ambient light conditions.

When an object is detected in the left side blind zone, the side object sensor module sends a message to the right sensor through serial data. The right sensor then supplies voltage to illuminate the visual indicator on the left side outside rear view mirror. When an object is detected in the right side blind zone, the right side object sensor will supply a voltage to illuminate the visual indicator on the right side outside rear view mirror. Each sensor is supplied B+ and ground. Ground is provided through the outside rearview mirror harness.

Diagnostic Aids

• When the ignition is turned on, or the engine is started, both outside rearview mirror displays will briefly come on to indicate that the system is operating.
• The conditions for disabling the side blind zone alert system are captured by DTCs. The drivers information center will display Service Side Detection System if one of the sensors has failed.
• The side blind zone system will be disabled if the driver has selected the Off mode through vehicle personalization menus. The selected mode is retained over ignition cycles. A driver information center message stating that the side blind zone system is off shall be displayed and the outside mirror indicators will be OFF.
• The side blind zone may be temporarily unavailable if a blockage condition exists (i.e. mud/snow buildup in front of the sensor). A driver information message "Side Detection System Unavailable" will be displayed. The side blind zone system transitions back to the normal operating state when the blockage is removed. Bumper sticks, fascia damage, labels, and heavy rain storms may also cause this condition. The blockage determination is performed with the vehicle in a drive gear.
• Because the sensors are NOT identical, they must NOT be swapped from one side of the vehicle to the other in an attempt to isolate a concern. Sensors should also NOT be swapped from one vehicle to another.
• The side blind zone system is designed to ignore stationary objects; however, the system may occasionally detect guard rails, signs, trees, shrubs, or other stationary objects as an object in the blind zone. This is normal system operation and does not require service.
• The side blind zone system may indicate an object in the blind zone if a trailer is attached to the vehicle, or a bicycle or object is extending out to either side of the vehicle. This is normal operation and does not require service.

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 the scan tool can communicate with the left side object sensor.

• If the scan tool can not communicate with the left side object sensor

Refer to Circuit/System Testing - Left Side Object Sensor Malfunction.

• If the scan tool can communicate with the left side object sensor

3. Verify DTC U18A6 is not present

• If DTC U18A6 is present

Diagnose this DTC first. Refer to Diagnostic Trouble Code List.

• If DTC U18A6 is not present

4. Ignition OFF, ignition ON.
5. Verify that both side blind zone alert system indicators located in the outside rearview mirrors briefly turn ON and then turn OFF during the system self test.

• If both side blind zone alert indicators do not briefly turn ON and OFF

1. Verify the system is enabled

• If disabled, refer to diagnostic aids for cause of disable.
• If enabled, refer to Circuit/System Testing - Side Object Indicator Malfunction.
• If only one indicator does not briefly illuminate during the self test

Refer to Circuit/System Testing - Side Object Indicator Malfunction.

• If both side blind zone alert indicators briefly turn ON and OFF

6. All OK.

Circuit/System Testing

Left Side Object Sensor Malfunction

1. Ignition OFF and all vehicle systems OFF. Disconnect the harness connector at the B218L Side Object Sensor Module - Left. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between ground circuit terminal 7 and ground.

• If 10 ohms or greater

1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms

3. Verify a test lamp illuminates between the B+ circuit terminal 8 and ground.

• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition Off.
2. Test for less than 2 ohms in the B+ circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the B218L Side Object Sensor Module - Left.
• If the test lamp illuminates

4. Ignition OFF and all vehicle systems OFF. Disconnect the It may take up to 2 minutes for all vehicle systems to power down.
5. Test for less than 2 ohms between the serial data circuit terminal 1 and the DLC terminal 1.

• If 2 ohms or greater

Repair the open/high resistance in the circuit.

• If less than 2 ohms

6. Replace B218L Side Object Sensor Module - Left.

Side Object Indicator Malfunction

1. Ignition OFF and all vehicle systems OFF, remove the appropriate outside rearview mirror glass and disconnect the P43 Side Object Detection Indicator connector. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal and ground.

• If 10 ohms or greater

1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms

3. Ignition ON, connect a test lamp between the control circuit terminal and the ground circuit terminal.
4. Verify the test lamp turns ON and OFF when commanding the Object Detection Alert Indicators ON and OFF with a scan tool.

• If the test lamp is always OFF

1. Ignition OFF, disconnect the harness connector at the B218R Side Object Sensor Module - Right.
2. Test for infinite resistance between the control 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 control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the B218R Side Object Sensor Module - Right.
• If the test lamp is always ON

1. Ignition OFF, disconnect the harness connector at the B218R Side Object Sensor Module - Right, ignition ON.
2. Test for less than 1 V between the control circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit
• If less than 1 V, replace the B218R Side Object Sensor Module - Right.
• If the test lamp turns ON and OFF

5. Test or replace the appropriate A9 Outside Rearview Mirror Glass

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Outside Rearview Mirror Glass Replacement
• Control Module References for side object sensor module replacement, programming and setup.

READ NEXT: