Rear Cross Traffic Alert System Malfunction
Rear Cross Traffic Alert 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 Instructions provides an overview of each diagnostic category.
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. When an object is detected in the rear cross traffic zone, the module will send out a signal through serial data communication to turn on the visual icons and also audio chime or haptic notification. Each sensor is supplied B+ and ground. The right sensor receives an additional ground. Both sensors communicate independently on the serial data line. The serial data enters the left sensor in a pass-thru configuration, that connects to the right sensor. The scan tool is able to individually communicate with each sensor.
Diagnostic Aids
* The rear cross traffic alert system uses the same side blind zone sensors so a malfunction may affect either or both systems.
* The conditions for disabling the rear cross traffic alert system are captured by DTCs. The drivers information center will display Service Side Detection System if one of the sensors has failed.
* The rear cross traffic system can be disabled if any off the following occur:
- 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 Rear Cross Traffic System Alert Off shall be displayed.
- There is a loss of serial data communication with a sensor or between modules.
- A blockage condition exists (i.e. mud/snow buildup in front of the sensor). A driver information message stating that the side detection system is temporarily unavailable will be displayed. The rear cross traffic 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.
- The rear cross traffic alert system will read the GPS latitude and longitude on the serial data bus and calculate if the vehicle is within a Radio Astronomy zone. These zones are located in Europe and Japan and require the sensors to be turned off. The "Side Detection System Unavailable" message will be displayed to the driver when this occurs.
* Because the sensors are identical, they may be swapped from one side of the vehicle to the other in an attempt to isolate a concern. Sensors should NOT be swapped from one vehicle to another.
* The rear cross traffic alert system is designed to ignore stationary objects; however, the system may occasionally detect pedestrians, shopping carts, or other objects. This is normal system operation and does not require service.
* The rear cross traffic alert system may indicate an object if a trailer is attached to the vehicle, or a bicycle or object is extending out to either side of the vehicle. The system may also temporarily disable the system and display the "Side Detection System Unavailable" message.
Reference Information
Schematic Reference
Object Detection Schematics [1][2]Collision Avoidance and Parking Assist Systems
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Object Detection Description and Operation (with Active Safety System - UGN) Object Detection Description and Operation (with Active Safety System - UGN)Object Detection Description and Operation (with rear vision camera - UVC) Object Detection Description and Operation (with rear vision camera - UVC)Object Detection Description and Operation (with front and rear park assist - UD5) Object Detection Description and Operation (With Front and Rear Park Assist - UD5)Object Detection Description and Operation (with rear park assist - UD7) Object Detection Description and Operation (With Rear Park Assist - UD7)Object Detection Description and Operation (with side blind zone alert - UFT) Object Detection Description and Operation (with side blind zone alert - UFT)Object Detection Description and Operation (with rear cross traffic alert - UFG) Object Detection Description and Operation (With Rear Cross Traffic Alert - UFG)Object Detection Description and Operation (with lane departure warning - UFL) Object Detection Description and Operation (With Lane Departure Warning - UFL)Object Detection Description and Operation (with forward collision alert - UEU) Object Detection Description and Operation (With Forward Collision Alert - UEU)Object Detection Description and Operation (with Haptic Signal Motor Seat) Object Detection Description and Operation (with Haptic Signal Motor Seat)
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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the scan tool can communicate with the right side object sensor.
• If the scan tool can not communicate with the right side object sensor
Refer to Circuit/System Testing - Right Side Object Sensor Malfunction.
• If the scan tool can communicate with the right side object sensor
3. 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
4. Verify that the rear cross traffic indicators and haptic seats (or audio beep) alerts turn ON and then turn OFF when commanding the Object Detection Alert Indicators ON and OFF with a scan tool.
• If alert indicators do not turn ON and OFF
1. Verify the system is enabled.
• If disabled, refer to diagnostic aids for cause of disable.
• If enabled refer to Seat Haptic Signal Motor Malfunction Seat Haptic Signal Motor Malfunction, audio system malfunction, or display malfunction.
• If indicators turn ON and OFF
5. All OK.
Circuit/System Testing
Right Side Object Sensor Malfunction
1. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Disconnect the harness connector at the B218R Side Object Sensor Module - Right.
2. Test for less than 10 ohms between the following ground circuit terminals and ground.
* Terminal 3
* Terminal 8
• 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 5 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 B218R Side Object Sensor Module - Right.
• If the test lamp illuminates
4. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down.
5. Test for less than 2 ohms in each of the serial data circuits end to end between the control module harness connector terminal 7 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 B218R Side Object Sensor Module - Right.
Left Side Object Sensor Malfunction
1. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Disconnect the harness connector at the B218L Side Object Sensor Module - Left.
2. Test for less than 10 ohms between ground circuit terminal 8 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 5 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. It may take up to 2 minutes for all vehicle systems to power down.
5. Test for less than 2 ohms in each of the serial data circuits end to end between the control module harness connector terminal 2 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.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Side Object Sensor Module Replacement Service and Repair
* Control Module References Control Module References Side Object Sensor Module replacement, programming and setup