The object alarm system monitors the distance and how close a vehicle is to an object when backing up in a parking maneuver. The object alarm system will notify the driver of any objects of interest when backing up at speeds less than 5 km/h (3 mph). The distance between a vehicle and an object of interest is monitored by the 4 ultrasonic sensors located in the rear bumpers of the vehicle. The object sensors receive the echo signals reflected off an object of interest while the vehicle is backing up at speeds less than 5 km/h (3 mph). The rear object sensor control module receives the vehicle speed input from the ECM via the vehicle speed signal circuit. When the backing up speed exceeds 5 km/h (3 mph), the rear parking assist (RPA) system is disabled. The object detection system uses visual displays and audible warnings from the radio speakers to warn the driver of an object of interest within the defined field of view. The body control module (BCM) controls the RPA chime function via the chime control circuit and sends serial data request to the radio to activate the chime as needed. The visual RPA display comprises of two amber and one red indicators. These indicators illuminate based on the vehicle distance to the object of interest. When the RPA system is activated, the RPA display first performs a bulb check before any normal operation. The object sensor is a three wire sensor comprising of the supply voltage circuit, signal circuit and the low reference circuit. Power and ground is provided to the object sensors from the rear object sensor control module via the object sensor supply voltage circuit and low reference circuit. The typical object sensor signal circuit voltage when the system is active is between 7.2 V-9.2 V. The object detection system is initiated when the rear object sensor control module receives the transmission reverse input from the BCM via the backup lamp supply voltage circuit.

Schematic Reference

Object Detection Schematics

Connector End View Reference

Object Detection Connector End Views

Description and Operation

Object Detection Description and Operation

Electrical Information Reference

The Diagnostic Indicator Pattern 1 is a confirmation that the object alarm system has successfully entered the diagnostic mode. If the Diagnostic Indicator Pattern 1 does not display after an attempt to enter the diagnostic mode, it may be as a result of not entering the system diagnostic mode successfully or an RPA diagnostic input circuit fault is present. After the Diagnostic Indicator Pattern 1 is displayed, observe the RPA display for the next Diagnostic Indicator Pattern displayed. The indicator pattern displayed after the Diagnostic Indicator Pattern 1 is the diagnostic indicator pattern that actually needs be diagnosed. Proceed to the appropriate Diagnostic Pattern in this table. Refer to Diagnostic Trouble Code (DTC) Displaying.

Diagnostic Indicator Pattern 1

1. Enter the diagnostic mode. Refer to Diagnostic Trouble Code (DTC) Displaying.
2. Verify that the Diagnostic Indicator Pattern 1 does not display as shown in the diagnostic indicator list. Refer to Diagnostic Trouble Code (DTC) Displaying.

⇒	If the Diagnostic Indicator Pattern 1 displays after entering the diagnostic mode, proceed to the next Diagnostic Indicator Pattern displayed.

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If the Diagnostic Indicator Pattern 1 does not display after successfully entering the diagnostic mode, test the rear park assist diagnostic input circuit terminal 16 for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the rear object sensor control module.

Diagnostic Indicator Pattern 2, 3, 4 and 5

1. Ignition OFF, disconnect the harness connector at the suspect rear object sensor.
2. Test for less than 1 ohm between the low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance.

3. Ignition ON, with the transmission in reverse, test for 8.2V-8.8V between the supply voltage circuit terminal 3 and the low reference circuit terminal 2.

⇒	If less than the specified range, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear object sensor control module.

⇒	If greater than the specified range, test the supply voltage circuit for a short to battery. If all circuit tests normal, replace the rear object sensor control module.

4. Ignition ON, with the transmission in reverse, test for 7.2V-9.2V between the signal circuit terminal 1 and the object sensor low reference circuit terminal 2.

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear object sensor control module.

⇒	If greater than the specified range, test the signal circuit for a short to battery. If all circuit tests normal, replace the rear object sensor control module.

5. If all circuits test normal, test or replace the suspect rear object sensors.

Diagnostic Indicator Pattern 6

1. Ignition OFF, disconnect the harness connector at the rear object sensor control module.
2. Ignition ON, test for 9.5V between the chime control circuit terminal 22 and ground.

⇒	If less than the specified value, test the chime control circuit for a short to ground or an open/high resistance. If all circuits test normal, replace the body control module (BCM).

⇒	If greater than the specified value, refer to Reduced Volume - One or More Speakers.

Diagnostic Indicator Pattern 7

Important: When entering the diagnostic mode, it is necessary to follow the instructions as indicated. Refer to Diagnostic Trouble Code (DTC) Displaying. If the vehicle is not shifted into reverse within 5 seconds after turning the ignition ON, the diagnostic mode will still be initiated but a reverse input wiring fault will be registered as Diagnostic Indicator Pattern 7 as shown in the indicator list.

Verify that the Diagnostic Indicator Pattern 7 displays as shown in diagnostic indicator list.

Diagnostic Indicator Pattern 8 and 9

Important: Diagnostic indicator patterns 8 or 9 are displayed in sequence of diagnostic indicator patterns 2, 3, 4 and 5.

1. While still in the diagnostic mode, disconnect the rear object sensors one at a time and verify that the indicator pattern 8 or 9 does not display after the suspect sensors has been disconnected. When the suspect sensors is disconnected, the indicator pattern 8 or 9 should no longer be displayed.

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If the indicator pattern 8 or 9 continues to display after each sensor has been disconnected and reconnected, test the object sensor supply voltage circuit and the low reference circuit for a short to ground or an open/high resistance. If circuit tests normal, replace the rear object sensor control module.

⇒	If the indicator pattern 8 and 9 does not display after disconnecting the suspect sensor, replace the suspect sensor.

2. If all circuits test normal, replace the object sensor control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.