P077B
DTC P077B
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.
DTC Descriptor
DTC P077B
- Output Speed Sensor Direction Incorrect
Diagnostic Fault Information
Typical Scan Tool Data
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 2ML70 - Automatic Transmission
Connector End View Reference
Component Connector End Views Connector End Views By Name
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Programming and Relearningfor scan tool information.
Special Tools
J 38522 Variable Signal Generator
Circuit/System Verification
1. Verify that DTCs P0721, P0722, P0723, P0966, P0967, P0969, P0970, P0971, P0973, P0974, P0976, P0977, P2720, P2721, P2728, P2729, or P2730 are not set.
• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Operate the vehicle at 16-32 km/h (10-20 mph) while observing the Transmission Data OSS Direction parameter on the scan tool. The OSS Direction parameter should match vehicle direction.
• If the OSS parameter corresponds with the vehicle direction and the DTC is set in the hybrid powertrain control module and not the transmission control module, replace the hybrid powertrain control module.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B14A automatic transmission output shaft speed sensor. Inspect the automatic transmission output shaft speed sensor, harness, and connector pins for metallic debris and the hybrid direct, 2-3-4 clutch housing assembly machined teeth for damage or misalignment. Even one bent or misaligned tooth, and or contact with the automatic transmission output shaft speed sensor, may cause this DTC to set. Proper torque of 9-13 Nm (80-115 lb in) to the automatic transmission output shaft speed sensor mounting bolt is critical to proper output speed sensor operation. The hybrid system is very sensitive to the OSS signal for overall operation.
• If damage is observed, replace the damaged component.
2. Ignition ON, test for 8.3-9.3 V between the OSS supply voltage circuit terminal A and ground.
• If less than the specified range, test the OSS supply voltage circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the Q8 control solenoid valve assembly.
• If greater than the specified range, test the OSS supply voltage circuit for a short to voltage. If the circuit tests normal, replace the Q8 control solenoid valve assembly.
3. Ignition Off, connect the red lead of J 38522 - variable signal generator to the OSS signal circuit terminal B and the black lead to the OSS supply voltage circuit terminal A.
4. Adjust the J 38522 - variable signal generator Signal to 8V, the Frequency to 120 and the Percent Duty Cycle to 50.
5. Ignition ON, verify the Transmission OSS parameter is between 100-400 RPM.
• If the Transmission OSS parameter is not within the specified range, test the Transmission OSS signal circuit for an open/high resistance, short to ground, or a short to voltage. If the circuit tests normal, replace the Q8 control solenoid valve assembly.
• If the Transmission OSS parameter is within the specified range, replace the B14A automatic transmission output shaft speed sensor.
Component Testing
Control Solenoid Valve and Transmission Control Module Assembly Output Shaft Speed Input Test Control Solenoid Valve and Transmission Control Module Assembly Output Shaft Speed Input Test.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Output Speed Sensor Replacement 2ML70 - Automatic Transmissionfor Automatic Transmission Output Shaft Speed Sensor
* Control Module References Programming and Relearningfor Control Solenoid Valve Assembly replacement, programming and setup.
* Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection.