Wheel Speed Sensor Input

Wheel speed sensor input is used to determine distanced traveled, vehicle speed as well as direction.

Mark I navigation systems monitored both the left and right front wheel speed sensors. The left and right signals are used to determine direction in turns by comparing the speed difference between the signals. This was due to the fact the Mark I system did NOT use a gyro sensor.

Mark II and III systems only use one wheel speed signal. The wheel speed signal for the E46 comes from the left rear wheel. On all other vehicles, the left front wheel speed sensor is used.

Wheel speed is needed by the navigation to determine distance traveled especially when the overhead view is obstructed to the satellites (i.e tunnels, trees etc.). This allows the navigation computer to have an uninterrupted measurement of distance.

NOTE: The installation of aftermarket wheels of improper size can greatly affect the accuracy of the navigation system. When investigating complaints of navigation inaccuracy, always be sure to check for proper tire size.

Fig 1: Identifying Wheel Speed Sensor Signals (Example Of Mark I)

Courtesy of BMW OF NORTH AMERICA, INC.