For 1990-2009 cars

## Rear Parking Assist Malfunction LWB SWBRHD

### Diagnostic Fault Information

• | 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.

### Circuit/System Description

The rear park assist system is designed to assist the driver when reversing and should not be used as a substitute for safe driving practices. The rear park assist system is equipped with an object alarm module, a speaker and four ultrasonic sensors. The ultrasonic sensors operate both as transmitters and receivers. The driver is alerted to approaching objects by a sequence of pulses or continuous tones from the rear object alarm speaker.

### Reference Information

#### Schematic Reference

Object Detection Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Object Detection Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

• | Connector Repairs

### Circuit/System Verification

1. Park brake OFF, transmission in REVERSE, the park assist system should turn on.
2. Place a suitable object behind the vehicle, the rear object alarm speaker should sound.

### Circuit/System Testing

1. Ignition OFF, disconnect the external relay.
2. Ignition ON, engine OFF, transmission in REVERSE, verify a test lamp illuminates between the reverse control circuit terminal 1 and ground.

⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, refer to Backup Lamps Malfunction

3. Test for less than 5 Ω between the ground circuit terminal 3 and ground.

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

4. Test for greater than 11.5 V between the ignition circuit terminal 5 and ground.

⇒ | If less than the specified range, test the ignition circuit for an open/high resistance or short to ground.

5. Ignition OFF, connect the external relay.
6. Disconnect the X1 harness at the rear object alarm module.
7. Ignition ON, engine OFF, transmission in REVERSE, test for 9 - 16 V between the B+ circuit terminal 2 and ground.

⇒ | If not within the specified range, test the B+ circuit for a short to voltage, short to ground or an open/high resistance. If the circuit tests normal, replace the external relay.

8. Test for less than 5 Ω between the ground circuit terminal 1 and ground.

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

9. Ignition OFF, disconnect the harness at the rear object alarm speaker.
10. Place a suitable object behind the vehicle.
11. Connect a test lamp between the rear object alarm module speaker voltage signal terminal 4 and low reference circuit terminal 3.
12. Connect the X1 harness at the rear object alarm module.
13. Ignition ON, engine OFF, transmission in REVERSE, the test lamp should illuminate.

⇒ | If the test lamp does not illuminate, test the voltage signal circuit for a short to ground or an open/high resistance and test the low reference circuit for an open/high resistance. If the circuits test normal, replace the rear object alarm module.

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

### Component Testing

1. Ignition OFF, disconnect the harness at the rear object alarm speaker.
2. Apply 2.5 V to the voltage circuit terminal 4.
3. Apply ground to the ground circuit terminal 3, the speaker should sound.

⇒ | If the speaker does not sound replace the rear object alarm speaker.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for Rear Object Alarm Module or Rear Object Alarm Speaker replacement, setup, and programming.