E60, E61, E63, E64 - Park Distance Control Ultrasonic Sensors

Installation location 

There are 4 ultrasonic sensors in each of the front and rear bumpers (illustration shows E60).

Fig 1: Locating Park Distance Control Ultrasonic Sensors: E60, E61, E63, E64

Courtesy of BMW OF NORTH AMERICA, INC.

Construction 

Compared to earlier systems, the ultrasonic sensors have a circular membrane (larger effective range and lower sensitivity to moisture). The membrane is always painted in the vehicle's body color. The ultrasonic sensors in the front and rear bumpers are electrically identical. The difference between the front and rear ultrasonic sensors is the arrangement of the plug connection, which is due to the specific installation location.

How it works 

The ultrasonic sensors are activated by the PDC control unit, either in combined transmit and receive mode or in pure receive mode.

1. Combined transmit and receive mode
   
   In combined transmit and receive mode, the 8 ultrasonic sensors first transmit a package of ultrasonic impulses. Each ultrasonic sensor then receives the echo pulse reflected by an object within the effective range. This echo pulse is amplified in the ultrasonic sensor and sent to the PDC control unit in the form of a digital signal. The PDC control unit calculates the distance from the object from the time lag of the echo pulse.
2. Receive mode
   
   In receive mode, the ultrasonic sensor receives the echo pulses transmitted by the adjacent ultrasonic sensors. The PDC control unit is then able to evaluate the signals of up to 3 ultrasonic sensors (triangulation). The evaluation of these signals from several ultrasonic sensor is used to calculate the minimum distance between the vehicle and the object.