Parking Aid Sensors

WARNING: This page is about a different car, the 2011 Jaguar XKR, 2011 Jaguar XK, 2010 Jaguar XKR, and 2010 Jaguar XK. However, it is still accessible from the selected car via links, so may be relevant.

Courtesy of JAGUAR CARS, INC.

Four sensors are positioned in the rear bumper and four in the front bumper (if fitted). The front sensor housings are glued into position; the rear sensor housings are welded into position. The sensor bodies are then clipped into the housings from the rear.

Each sensor has a three pin connector which connects into a common harness linking all four sensors. The three pins of each connector provide the sensor a negative feed, a positive feed and a signal line. The rear parking aid harness connects to the main vehicle body harness. The front parking aid harness connects to the left-hand (LH) engine compartment harness.

Each sensor comprises a plastic housing which contains a piezoelectric disc. The disc resonates at a frequency of approximately 50 kHz, producing an ultrasonic signal output. The disc also receives the reflected echo signal.

Each sensor has two modes of operation; combined transmitter and receiver mode or receiver mode only. The control module controls the operating mode of each sensor by the output of a digital signal on the signal line.

In the combined mode, the sensor emits a series of ultrasonic impulses and then switches to receiver mode to receive the echo reflected by an obstacle in the detection range. These echo signals are amplified and converted from an analogue signal to a digital signal by the sensor. The digital signal is then transmitted to the control module and compared with preprogrammed data stored in an electrically erasable programmable read only memory (EEPROM) within the module.

The module receives this data via the signal line from the sensor and calculates the distance to the obstacle according to the elapsed time between the transmitted and received impulse. The duration of the impulse transmission is determined by the control module. The frequency of the impulse is determined by the sensor.

In the receiver mode, the sensor will receive impulses that were emitted by adjacent sensors. The control module uses this information to precisely determine position and distance of the obstacle.