Spark

Rear Parking Assist Malfunction

The rear object sensor control module is supplied ignition voltage from the I/P fuse block. When the transmission is in reverse the system is turned on, ignition voltage is supplied through the reverse lamp switch. The object alarm sensors are supplied with signal circuits referenced from 8 volts by the rear object sensor control module and low reference circuits. The object alarm module is supplied with an 8 volt power supply and low reference from the module. The alarm control circuit is an 8 volt circuit that is pulse width modulated low to activate the alarm.

The park assist system is capable of performing an object detection sensor self test. While in the sensor self test mode the park assist module will verify inputs from the object detection sensors. The park assist module indicates sensor status using the system alarm. If both sensor signals are being received by the rear park assist module 1 single short tone will be activated. When one or both sensor signals are not received the module will respond by activating the alarm with 1 tone repeated for a left sensor fault and 2 tones repeated for a right sensor fault. If both sensors are faulted the module will respond by activating the alarm with 1 tone repeated 3 times then 2 tones repeated 3 times then repeat the sequence.

To enter the object sensor self test complete the following steps:

1. Turn the ignition ON.
2. Apply and release the parking brake 3 times within 10 seconds after the ignition is turned ON.
3. The system will be in the object sensor self test mode.
4. To exit the object detection sensor self test mode turn the ignition OFF.

1. Ignition ON, with the area behind the vehicle clear of any objects which may activate the park assist alarm, shift the transmission to reverse. The object alarm should sound 1 short tone.

⇒	If not the specified value, refer to object alarm system circuit test.

2. Perform the object detection sensor self test procedure in order to verify the sensor inputs to the module. Refer to diagnostic aids.

⇒	If the self test mode indicates that either sensor input has failed, refer to object alarm sensor circuit test.

Object Alarm System Circuit Test

1. Ignition OFF, disconnect the harness connector at the rear object sensor control module.
2. Test for less than 1.0 Ω between the ground circuit terminal 16 and ground.

⇒	If greater than the specified value, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 8 and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

4. Park brake applied, transmission in reverse, verify that a test lamp illuminates between the reverse lamp control circuit terminal 5 and ground.

⇒	If the test lamp does not illuminate, test the reverse lamp control circuit for a short circuit to ground or an open/high resistance.

5. Ignition OFF, connect the harness connector at the rear object sensor control module.
6. Disconnect the harness connector at the object alarm module.
7. Test for less than 1.0 Ω between the low reference circuit terminal 3 and ground.

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

8. Ignition ON, test for 7.5-8.2V between the 8V reference circuit terminal 1 and ground.

⇒	If less than the specified range, test the 8V reference 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 8V reference circuit for a short to voltage. If the circuit tests normal, replace the rear object sensor control module.

9. Connect a test lamp between the signal circuit terminal 2 and ground. The test lamp should not illuminate.

⇒	If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the rear object sensor control module.

10. Test for infinite resistance between the signal circuit terminal 2 and ground.

⇒	If less than the specified value test the signal circuit for a short circuit to ground. If the circuit tests normal, replace the rear object sensor control module.

11. Ignition OFF, place an object less than 0.4m away from the rear bumper.
12. Connect a test lamp between the 8V reference circuit terminal 1 and the signal circuit terminal 2.
13. Ignition ON, park brake applied, transmission in reverse, the test lamp should illuminate.

⇒	If the test lamp does not illuminate, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the rear object sensor control module.

14. If all circuits test normal, replace the object alarm module.

Object Alarm Sensor Circuit Test

1. Ignition OFF, disconnect the harness connectors at the object alarm sensor.
2. Test for less than 1.0 Ω between the low reference circuit terminal 2 and ground.

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

3. Ignition ON, park brake applied, transmission in reverse, test for 7.5-8.2 V between the object alarm sensor signal circuit terminal 1 and ground.

⇒	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 voltage. If the circuit tests normal, replace the rear object sensor control module.

4. If all circuits test normal, replace the appropriate object alarm sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.