2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 1834
Circuit/System Description
The output speed sensor assembly has 2 internal hall-effect type sensors, and is capable of sensing both speed and direction. The output speed
sensor mounts to the A/T rear case assembly and is connected to the control solenoid valve assembly through a wire harness and connector. The
sensor faces the hybrid direct, 2-3-4 clutch housing assembly machined teeth surface. The sensor receives 8.3-9.3 volts on the OSS supply voltage
circuit from the transmission control module. 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 transmission
control module for speed and direction and is transmitted through the serial data circuits to the engine control module (ECM) and the hybrid
powertrain control module. The ECM, hybrid powertrain control module, and transmission control module compare the OSS signal with the anti
lock brake system wheel speed sensor signal. The hybrid powertrain control module also compares the output shaft direction with the drive motor 1
and drive motor 2 direction.
Conditions for Running the DTC
* The OSS speed parameter is less than 50 RPM.
* The drive motor estimated output speed is greater than 50 RPM.
Conditions for Setting the DTC
The hybrid powertrain control module or the transmission control module detects an incorrect OSS direction.
Action Taken When the DTC Sets
Hybrid Powertrain Control Module
The hybrid powertrain control module calculates OSS direction based on drive motor 1 and drive motor 2 direction.
Transmission Control Module
* The transmission control module freezes transmission adaptive functions.
* The transmission control module turns OFF all solenoids.
Conditions for Clearing the DTC
Hybrid Powertrain Control Module
P077B is a Type A DTC.
Transmission Control Module
P077B is a Type A DTC.
Diagnostic Aids
Inspect the output speed sensor, harness, connector and control solenoid valve assembly pins for metallic debris and output shaft machined face for
damage or misalignment. Proper torque of the output speed sensor mounting bolt is critical to proper output speed sensor operation. Use a terminal
test kit for any test that requires probing the control solenoid valve assembly harness connector or a component harness connector.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics (See: Transmission and Drivetrain/Automatic Transmission/Transaxle/Diagrams)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Electrical Information Reference
