Transmission Output Speed Sensor (Speed Of The Output Shaft)

WARNING: This page does not describe the selected car, but rather 12 other vehicles, including the 2014 Volvo XC90, 2013 Volvo XC90, 2012 Volvo XC90, 2011 Volvo XC90, and 2010 Volvo XC90. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Transmission Speed Sensor

Courtesy of VOLVO CARS CORPORATION

The transmission output shaft speed sensor is positioned on the transmission housing. The sensor is electro-magnetic and acts on a toothed pulse wheel. The sensor provides signals to the transmission control module (TCM) about the vehicle speed. The transmission speed sensor is an active sensor and is supplied with 12 V. When the pulse wheel rotates, the sensor generates a pulsed current (quadratic wave) where the strength of the current depends on the position of the pulse wheel. The signals from the coil in the sensor are then effected by a magnetic resistance element, which generates a current which oscillates between 7 mA and 14 mA, and the frequency of which increase with speed. The control module calculates the transmission output speed using the signals from the sensor. The signal is compared with the signal from the transmission input speed sensor and is used to calculate the gear ratio as well as for diagnostics.

There are diagnostics for the transmission output speed sensor.