Driving Aids: Other Land Rover Discovery II

General

Park Distance Control (PDC) is introduced on vehicles from 03 model year. 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 and is not designed as a crash avoidance system or a replacement for visual interpretation by the driver.

The system comprises four ultrasonic sensors in the rear bumper, an ECU, a fascia mounted momentary switch and a 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 de-activate the PDC system if operation is not required or the vehicle has a trailer attached.

Scheme 7

The PDC ECU is located in the LH side of the luggage compartment. A bracket is attached to the 'E' post, behind the trim panel and provides for the attachment of the ECU and the PDC sounder.

On vehicles without rear air conditioning, the bracket is located inboard on the LH 'E' post, adjacent to the luggage compartment trim panel. On vehicles with rear air conditioning, the bracket is located outboard on the LH 'E' post, adjacent to the outer body panel.

The bracket has integral studs which provide for the attachment of the ECU with nuts. The ECU is located with the harness connectors uppermost to assist access. The PDC sounder is located on the opposite side of the bracket and is secured with screws, lock washers and nuts.

Scheme 8

CONNECTOR C0958 PINS REFERENCE

CONNECTOR C0957 PINS REFERENCE

Inputs and Outputs

Two connectors provide the interface between the PDC ECU and the external PDC components.

The ECU receives inputs from the following

1. Reverse lamp circuit - for system activation when reverse gear is selected
2. PDC switch - for activation and de-activation of the system
3. Ignition switch - power supply for system operation. The ECU outputs to the following
4. Sensors - power and ground connections
5. Sensor - digital signal transmit and receive signals
6. Sounder - signal for sounder operation
7. PDC Switch - power supply for switch LED operation.

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.

Scheme 9

Scheme 10

Scheme 11

1. Remove loadspace LH side trim casing access panel.
2. Remove 2 bolts securing parking aid ECU mounting bracket to body and maneuver ECU and bracket assembly from behind trim casing.
3. Disconnect multiplug from ECU.
4. Remove 2 nuts securing ECU to bracket.
5. Remove ECU.

Refit

1. Fit ECU to mounting bracket and fit and tighten nuts.
2. Connect ECU multiplug.
3. Maneuver ECU and mounting bracket assembly behind trim casing, align, fit bolts and tighten to 25 Nm (18 lbf.ft).
4. Fit access panel.

Scheme 12

Scheme 13

Scheme 14

Scheme 15

1. Remove loadspace LH side trim casing access panel.
2. Remove 2 bolts securing parking aid ECU mounting bracket to body and maneuver ECU and bracket assembly from behind trim casing.
3. Disconnect multiplugs from parking aid ECU and parking aid sounder.
4. Remove 2 nuts and bolts securing parking aid ECU to bracket and remove the ECU.
5. Remove 2 screws securing parking aid sounder to bracket and remove the sounder.

1. Fit parking aid sounder to the bracket and secure with screws.
2. Fit parking aid ECU to the bracket and secure with nuts and bolts.
3. Connect multiplugs to parking aid ECU and parking aid sounder.
4. Maneuver ECU and mounting bracket assembly behind trim casing, align, fit bolts and tighten to 25 Nm (18 lbf.ft).
5. Fit and secure loadspace access panel.

Scheme 16

Scheme 17

1. Remove rear bumper assembly. Refer to «REMOVE»(ref-207934-S33596174242005120400000) .
2. Remove 7 bolts and 5 screws securing closing panel and remove panel.
3. Disconnect multiplug from sensor.
4. Release and remove sensor and sensor housing.

1. Clean sensor location on bumper.
2. Fit sensor housing to bumper, ensuring lug on housing is aligned with cut-out in bumper.
3. Fit and secure sensor to housing.
4. Connect multiplug.
5. Fit closing panel and secure with bolts and screws.
6. Fit bumper assembly.

Refer to REFIT .

Scheme 18

1. Remove tail lamp from bumper.
2. Disconnect multiplug from sensor.
3. Release and remove sensor and sensor housing.

1. Clean sensor location on bumper.
2. Fit sensor housing to bumper, ensuring lug on housing is aligned with cut-out in bumper.
3. Fit and secure sensor to housing.
4. Connect multiplug.
5. Fit tail lamp.