GENERAL
PDC provides an audible warning to the driver when any obstacles are in the path of the vehicle during a reversing maneuver. The purpose of the system is to assist the driver when parking or maneuvering in restricted space. It is not designed as a crash avoidance system or a replacement for visual interpretation for the driver.
The system comprises four ultrasonic sensors in the rear bumper, a control module, a fascia mounted control switch and a rear sounder unit.
The system operates using ultrasonic signals which are transmitted by the sensors. The reflected echo from this output is received by the sensors and used by the PDC ECU to calculate the distance from an object.
The fascia mounted switch allows the driver to deactivate the PDC system, if operation is not required.
PDC ECU
The PDC ECU is located in the rear right hand side of the luggage compartment, behind the side trim panel.
The PDC ECU uses a single microprocessor to perform the following tasks
- Control Of The Ultrasonic Sensors
- Monitoring Of The Sensors
- Evaluation Of Received Echo Signals From The Sensors
- Noise And Disturbance Suppression
- Control Of The PDC Sounder
- Monitoring Of The Sounder And Lead
- Control And Monitoring Of The Switch Status LED And Lead
- Evaluation And Monitoring Of The Control Inputs
- Management Of Diagnostic And Test Functions
- Monitoring Of Power Supply
- Communication Via Diagnostic Link
Scheme 15
The following tables give input/output information for the two harness connectors used on the PDC ECU.
| Pin No. | Description | InputOutput |
|---|---|---|
| 1 | Ignition switch power supply | Input |
| 2 | Sounder - Negative | Input |
| 3 | Not used | |
| 4 | PDC switch | Input |
| 5 | Not used | |
| 6 | Reverse gear signal | Input |
| 7, 8 and 9 | Not used | |
| 10 | Sounder - Positive 12V supply | Output |
| 11 and 12 | Not used | |
| 13 | PDC switch | Output |
| 14 and 15 | Not used | |
| 16 | Ground |
CONNECTOR C0958
| Pin No. | Description | InputOutput |
|---|---|---|
| 1 | Not used | |
| 2 | Sensor - RH Inner - Signal | Input |
| 3 | Sensor - LH Inner - Signal | Input |
| 4 | Sensor - RH Outer - Signal | Input |
| 5 | Sensor - LH Outer - Signal | Input |
| 6 and 7 | Not used | |
| 8 | Ground - All sensors | Input |
| 9 | Not used | |
| 10 | Power supply - All sensors | Output |
| 11 and 12 | Not used |
CONNECTOR C0957
INPUTS AND OUTPUTS
Two connectors provide the interface between the PDC ECU and the external PDC components.
The ECU receives inputs from the following
- Reverse lamp circuit - for system activation when reverse gear is selected
- PDC switch - fro activation and de-activation of the system
- Ignition switch - power supply for system operation.
The ECU outputs to the following
- Sensors - power and ground connections
- Sensors - digital signal transmit and receive signals
- Sounder - signal for sounder operation
- PDC switch - power supply for switch LED operation.
PDC SWITCH
Up to 2004 model year the PDC switch is located in the rear of the centre console. From 2004 model year the PDC switch is located in the fascia outboard of the steering wheel.
Scheme 16
Scheme 17
The PDC switch has a momentary, non-latching action, which switches a positive output from the PDC ECU to ground when pressed. This signal is used by the ECU to switch the PDC between the activated and deactivated conditions. The switch is connected to the PDC ECU via a harness connector which is integrated into the vehicle body harness.
The switch contains an LED, which illuminates when the system is active. If a fault exists in the PDC system, the ECU flashes the LED continuously while reverse gear is selected.
Scheme 18
The PDC sounder is controlled by the PDC ECU and emits a series of tones of varying frequency to inform the driver of the distance between the vehicle and a detected object.
The PDC sounder is located in the RH side of the rear luggage compartment. A bracket is attached to the `E' post, behind the trim panel and provides for the attachment of the PDC sounder and the PDC ECU. The sounder is connected to the PDC ECU via a harness connector.
DETECTION CALCULATION
When operating in the combined transmitter and receiver mode, the sensor outputs a number ultrasonic pulses and receives the reflected echo signal. The ECU amplifies the received echo signals and compares them with a preprogrammed threshold to calculate the distance to the object. This is achieved by determining the elapsed time between the transmission and reception of the ultrasonic signal.
When operating in receiver mode, the sensor receives echo signals transmitted by an adjacent sensor. This mode is used to improve the accuracy of the system.
The detection cycle consists of the ECU operating one sensor in the combined transmitter and receiver mode and transmitting a number of ultrasonic pulses. The ECU then switches the transmitting sensor and the adjacent sensor(s) to receiver mode. After a short time delay, this sequence is repeated using a different sensor to transmit the ultrasonic pulse and continues until all four sensors have output an ultrasonic signal. This sequence is completed in 100ms. The ECU uses several measurements of the same sensors to remove errors from the calculation.
If the object is directly behind a sensor, the distance is calculated using the time between the transmission and reception of the signal. If the object is positioned between two sensors, the ECU uses both signals to determine the correct distance using triangulation.
To perform the triangulation calculation, the ECU must know the distance between the individual sensors in the bumper. This information is stored in the ECU memory. From the received distance from each sensor and using the known distance between adjacent sensors, the ECU can calculate the minimum distance from the vehicle to the object.
When approaching several objects, the ECU recognizes the distance from the vehicle to the nearest object.