For 1990-2009 cars

## Object Alarm Sensor Malfunction Holden Genuine Accessory

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using the 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.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Object Alarm Sensor 8-Volt reference | 1, 2 | 1, 2 | 1, 2 | --
Object Alarm Sensor Low Reference | -- | 1, 2 | 1, 2 | --
1. Rear Object Detection System Inoperative. 2. Object Alarm Sensor Inoperative.

### Circuit/System Description

The object alarm module supplies 8 volts to the object alarm sensors through the reference/signal circuit and provides ground through the low reference circuit. Each sensor emits an ultrasonic frequency which is reflected off object located behind the vehicle. These reflections are received by the sensors.

The time difference between when the frequency was emitted and when the reflection is received is known as sensor ring time. The object alarm module uses the sensor ring time, which is received through the reference/signal circuit to calculate the distance and position of an object.

### Diagnostic Aids

The following is a brief description of potential causes which may aid in diagnosis:

Important: The recommended vehicle reversing speed is below five kph.

• | Attached Object- The object alarm module is detecting an object that is attached to the vehicle. Common items such as trailer, caravan or a bicycle rack may cause this concern.

• | Sensor Alignment - damage to the rear of the vehicle or a misaligned sensor may cause this concern. If the vehicle is damaged in a manner that causes the sensor to detect the bumper itself, the object alarm indicator will produce continuous buzzer sound. Carefully inspect the bumper, bumper mounting surface, and sensor retainers before continuing with normal diagnosis.

• | Sensor Disturbance - An outside interference is causing sensor movement. Such interference may be caused a heavy pounding, like that of a nearby jackhammer, or large changes in pressure, such as a large truck's air brakes.

• | Snow/Ice/Mud - One or more of the sensors is being blocked by snow, mud, ice, or other debris.

• | Sensor Ring Time - Each of the sensors emits an ultrasonic frequency. This frequency is reflected off of nearby objects, bouncing it back towards the vehicle bumper where it is received by the sensor. The time between the sensor emitting the frequency and the sensor receiving the reflection, known as sensor ring time, is used to determine the distance of nearby objects. Paint on a sensor may cause an excessive sensor ring time. Make sure the sensors are not painted.

### Reference Information

#### Schematic Reference

Object Detection Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Rear Object Detection Description and Operation Object Detection Description and Operation

#### Component View Reference

Object Detection Component Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

1. Ignition ON, engine OFF, Park brake ON, transmission in REVERSE, individually place a suitable object behind each sensor. Verify the correct operation of each object alarm sensor.

⇒ | If all object alarm sensors are malfunctioning, check the rear object detection system. Refer to Object Detection System Malfunction Rear Object Detection System Malfunction.

2. Ignition OFF, remove the malfunctioning object alarm sensor and swap locations with a good object alarm sensor. Connect the harness connector at both sensors.
3. Ignition ON, verify the operation of the swapped object alarm sensors.

⇒ | If the good object alarm sensor functions incorrectly at the new location, test the 8-volts reference circuit terminal 2 and low reference circuit terminal 1 of the object alarm sensor for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the object alarm module.

⇒ | If the good object alarm sensor functions correctly in the location where the malfunctioning sensor was previously installed, replace the malfunctioning object alarm sensor.

### Repair Instructions

For component removal and installation refer to the accessory fitting instructions.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.