Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle |
| • | Review Strategy Based Diagnosis |
DTC Descriptor
DTC P0721: Output Speed Sensor PerformanceDTC P0722: Output Speed Sensor Circuit No Signal
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
OSS Supply Voltage | P0721 | P0721 | -- | P0721 |
OSS Signal | P0721, P0722 | P0721, P0722 | P0721, P0722 | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open/High Resistance | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine running, normal operating temperature Parameter Normal Range: 0-7 000 RPM | |||
OSS Supply Voltage | Out of Range | Out of Range | OK |
Transmission OSS | 0 RPM | 0 RPM | 0 RPM |
Circuit/System Description
The output speed sensor (OSS) is a hall-effect type sensor. The sensor faces the output shaft machined teeth surface. As the output shaft rotates, the sensor produces a signal frequency based on the machined surface of the output shaft. This signal is transmitted to the Transmission Control Module (TCM). The TCM uses the OSS signal in connection with the input speed sensor signal to control engine torque, shift timing, and lock-up.
Conditions for Running the DTC
P0721
| • | The ignition voltage is between 10.2 V and 15.5 V. |
| • | The engine speed is greater than 400 RPM for 2 seconds. |
| • | The transmission is not in emergency mode. |
| • | Driving in D range. |
| • | TCM communication is normal. |
| • | Vehicle speed by ABS is greater than 30 km/h (19 MPH). |
P0722
| • | The ignition voltage is between 10.2 V and 15.5 V. |
| • | The engine speed is greater than 400 RPM for 2 seconds. |
| • | The transmission is not in emergency mode. |
| • | TCM communication is normal. |
| • | Driving in D range. |
Conditions for Setting the DTC
P0721
Deviation from calculated output speed is more than 15% for 1 s over 10 times.
P0722
| • | Deviation from calculated output speed is more than 300 RPM. |
| • | No output speed sensor pulse while receiving pulses on the input speed sensor. |
| • | No output speed sensor pulse when vehicle speed from ABS is more than 20 km/h (13 MPH) for 300 ms. |
Action Taken When the DTC Sets
| • | DTCs P0721 and P0722 are Type A DTCs. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM turns OFF all solenoids. |
| • | The TCM allows the vehicle after a stop to operate only in the second gear and "R" range. |
Conditions for Clearing the DTC
| • | DTCs P0721 and P0722 are Type A DTCs. |
| • | Output speed is greater than 300 RPM for more than 70 s. |
| • | Deviation from calculated output speed is less than 5% for more than 1 s. |
Diagnostic Aids
| • | Damage or misalignment of the counter drive gear machined teeth surface may cause a speed sensor malfunction. |
| • | Proper torque of the OSS mounting bolt is critical to proper OSS operation. |
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
Electrical Information Reference
Description and Operation
Transmission Component and System Description
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Operate the vehicle at 16 to 32 km/h (10 to 20 MPH) while observing the scan tool Transmission OSS parameter. The Transmission OSS should vary with the vehicle speed and not drop out.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observe from the Freeze Frame/Failure Records data.
Circuit/System Testing
Static Test
- Ignition OFF, remove the K71 Transmission Control Module (TCM).
- Test for more than 1 MΩ between the low reference circuit terminal 20 (X2) and the voltage supply circuit terminal 19 (X2).
- Test for infinite resistance between each terminal and the low reference circuit terminal 20 (X2) and also to the voltage supply circuit terminal 19 (X2).
- If all circuits test normal, test or replace the K71 Transmission Control Module (TCM). Verify the DTC does not reset.
| ⇒ | If less than the specified range, test the wiring harness for internal short. If the circuit test normal, replace the automatic transmission. |
| ⇒ | If less than the specified range, replace the wiring harness. |
| ⇒ | If the DTC resets, replace the automatic transmission. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Automatic transmission replacement, refer to Transmission Replacement |
| • | Control valve body replacement. Refer to Control Valve Body Replacement |
| • | Wiring harness, refer to Automatic Transmission Wiring Harness Replacement |
| • | TCM, refer to Control Module References |
| ⇒ | Perform the Transmission Adaptive Functions |
