• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
OSS Supply Voltage | P0722, P0723 | P0722, P0723 | P0722, P0723 | P0721, P077B |
OSS Signal | P0722, P0723 | P0722, P0723 | P0722, P0723 | P0721, P077B |
Circuit | Normal Range | Open/High Resistance | Short to Voltage |
---|---|---|---|
Operating Conditions: Engine running, normal operating temperature | |||
OSS Signal | Forward/Reverse | Out of Range | Out of Range |
OSS Supply Voltage | OK | Out of Range | Out of Range |
The output speed sensor (OSS) assembly has 2 internal hall-effect type sensors, and is capable of sensing both speed and direction. The OSS mounts to the A/T rear case assembly and is connected to the control solenoid (w/body and TCM) 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 (TCM). 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 OSS 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 TCM for speed and direction and is transmitted through the GMLAN circuits to the engine control module (ECM) and the hybrid powertrain control module (HPCM). The ECM, HPCM, and TCM compare the OSS signal with the ABS wheel speed sensor signal. The HPCM also compares the output shaft direction with the drive motor 1 and drive motor 2 direction.
• | The OSS is less than 50 RPM. |
• | The drive motor estimated output speed is greater than 50 RPM. |
The HPCM or the TCM detects an incorrect OSS direction.
The HPCM calculates OSS direction based on drive motor 1 and drive motor 2 direction.
• | The TCM freezes transmission adaptive functions. |
• | The TCM turns OFF all solenoids. |
P077B is a Type A DTC.
P077B is a Type A DTC.
Inspect the OSS, harness, connector and control solenoid (w/body and TCM) valve assembly pins for metallic debris and output shaft machined face for damage or misalignment. Proper torque of the OSS mounting bolt is critical to proper OSS operation. Use a terminal test kit for any test that requires probing the control solenoid (w/body and TCM) valve assembly harness connector or a component harness connector.
Automatic Transmission Controls Schematics
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information.
J 38522 Variable Signal Generator
⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
⇒ | The Output Shaft Direction parameter should match vehicle direction. |
⇒ | If the Output Shaft Direction parameter corresponds with the vehicle direction and DTC P077B is set in the HPCM and not the TCM, replace the HPCM. |
⇒ | If DTC P077B is also set in the TCM continue testing. |
⇒ | If less than 8.3 volts, test the OSS supply voltage circuit for an open/high resistance or short to ground. |
⇒ | If greater than 9.3 volts, test the OSS supply voltage circuit for a short to voltage. |
⇒ | If the OSS signal is not within the specified range, test the OSS signal circuit for an open/high resistance, short to ground, or a short to voltage. |
⇒ | If the circuit tests normal, replace the control solenoid (w/body and TCM) valve assembly. |
⇒ | If the OSS signal is within the specified range, visually inspect the OSS and the output shaft machined surface for damage or misalignment. If OK, replace the OSS. |
Perform the Control Solenoid Valve and Transmission Control Module Assembly Output Shaft Speed Input Test .
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming. |