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| • | 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 | P215C | P215C | P215C | P0721, P077B |
Low Reference | P215C | P215C | P215C | P0721, P077B |
Circuit | Normal Range | Open/High Resistance | Short to Voltage | Short to Ground |
|---|---|---|---|---|
Operating Conditions: Vehicle moving, normal operating temperature | ||||
OSS Signal | Forward/Reverse | Invalid/Unknown | Invalid/Unknown | Invalid/Unknown |
OSS Supply Voltage | OK | Out of Range | Out of Range | Out of Range |
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 transmission control module (TCM) 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 8.3-9.3 volts on the OSS supply voltage circuit from the 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 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 output speed sensor signal with the antilock brake system (ABS) wheel speed sensor signal. The TCM is part of the control solenoid valve assembly and is not serviced separately. The hybrid powertrain control module is part of the drive motor generator power inverter module and is not serviced separately.
The vehicle is ON.
The transmission control module detects an invalid Automatic Transmission Output Shaft Speed Sensor direction.
The hybrid powertrain control module 1 calculates vehicle direction based on the drive motor direction. The vehicle speed is calculated by the antilock brake system (ABS) wheel speed sensors.
DTC P0721 is a Type A DTC.
Automatic Transmission Controls Schematics
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information.
EL 38522 Variable Signal Generator
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.
| • | Automatic Transmission Wiring Harness and Output Speed Sensor Removal and Automatic Transmission Wiring Harness and Output Speed Sensor Installation for Automatic Transmission Output Shaft Speed Sensor replacement |
| • | Control Module References for Control Solenoid Valve Assembly and Transmission Control Module Assembly replacement, programming, and setup |
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