Circuit/System Description

WARNING: This page is about a different car, the 2019 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.

The A/Trans Output Speed Sensor Assembly has 2 internal hall-effect type sensors, and is capable of sensing both speed and direction. The output speed sensor is internal to the transmission and mounts to the A/Trans case assembly and is connected to the hybrid/EV powertrain control module 1 through the control solenoid valve assembly and transmission internal harness. The A/Trans Output Speed Sensor Assembly faces the park gear machined teeth surface. The sensor receives 5.0 volts on the OSS supply voltage circuit from the hybrid/EV powertrain control module 1. As the output shaft rotates, the sensor produces a signal frequency based on the machined surface of the output shaft.

The two sensor elements in the output speed sensor assembly are spaced approximately 1/2 a tooth apart.

When the vehicle is moving in a forward direction, sensor A detects a particular tooth before sensor B.
When the vehicle is moving in a reverse direction, sensor B detects a particular tooth before sensor A.

The electronics in the sensor combine the two signals and send a signal with a different pulse width. This signal is interpreted by the hybrid/EV powertrain control module 1 for speed and direction and is transmitted through the serial data circuits to the engine control module (ECM). The ECM, hybrid/EV powertrain control module 1, compare the output speed sensor signal with the anti-lock brake system (ABS) wheel speed sensor signal. The hybrid/EV powertrain control module 1 is part of the drive motor generator power inverter module and is not serviced separately.