For 1990-2009 cars

### Diagnostic Instructions

• | 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.

### DTC Descriptor

DTC P0722: Output Speed Sensor Circuit Low Voltage
DTC P0723: Output Speed Sensor Circuit Intermittent

### Circuit/System Description

The output speed sensor (OSS) system is a pulse generator consisting of a speed sensor assembly, located in the case extension, and a toothed vehicle speed sensor reluctor wheel, which is pressed onto the final drive carrier assembly. As the vehicle drives forward, the vehicle speed sensor reluctor wheel rotates. This rotation produces a variable AC signal in the pickup coil that is proportional to vehicle speed. The transmission control module (TCM) uses this signal in order to calculate vehicle speed, shift timing, and gear ratios.

### Conditions for Running the DTC

#### P0722

• | No TP sensor DTC P0120.

• | No ISS DTCs P0716 or P0717.

• | No OSS DTC P0723.

• | No IMS DTCs P1815, P1820, P1822, P1823, P1825 or P1826.

• | The engine run time is greater than 5 seconds.

• | The transmission is not in PARK or NEUTRAL.

• | The throttle position is 12 percent or greater.

• | The engine torque is greater than 70 N·m (52 lb ft).

• | Engine torque default values are not being used.

• | The transmission input shaft speed is 1,500-6,800 RPM.

#### P0723

• | No 1-2 Shift Solenoid Electrical DTC P0974.

• | No ISS DTCs P0716 or P0717.

• | No IMS DTCs P1815, P1820, P1822, P1823, P1825 or P1826.

• | The engine run time is greater than 5 seconds.

• | The transmission is not in PARK or NEUTRAL.

• | The transmission output speed is greater than 1,400 RPM for 2 seconds or greater.

• | One of the following conditions exist:

- | The transmission input shaft speed has not decreased for at least 2 seconds.

- | The transmission output shaft speed has not increased greater than 500 RPM for at least 2 seconds.

### Conditions for Setting the DTC

#### P0722

The transmission output shaft speed is 100 RPM or less for 3 seconds.

#### P0723

The transmission output shaft speed drops 1,300 RPM or greater for at least 3 seconds.

### Action Taken When the DTC Sets

• | DTC P0722 and P0723 are Type B DTCs.

• | The TCM commands maximum line pressure.

• | The TCM freezes transmission adaptive functions.

• | The TCM commands HSD1 OFF.

• | The TCM inhibits Autograde braking.

• | The TCM calculates vehicle speed from the automatic transmission input shaft speed sensor and commanded gear.

### Conditions for Clearing the DTC

DTCs P0722 and P0723 are Type B DTCs.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Transmission General Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Transmission Control Module Scan Tool Information

#### Special Tools

J 35616 GM-Approved Terminal Test Kit

### Circuit/System Verification

1. Raise and support the drive wheels.
2. Start and idle the engine.
3. Place the transmission in DRIVE.
4. Monitor Transmission OSS on the scan tool.
5. The Transmission OSS on the scan tool should be greater than 100 RPM.

### Circuit/System Testing

1. With the drive wheels supported, the engine running and the transmission in DRIVE ensure the Transmission OSS parameter on the scan tool is greater than 100 RPM.

⇒ | If the value is less than 100 RPM, disconnect the TCM connector and using the J 35616 GM-approved terminal test kit, connect the DMM between the OSS high signal and the OSS low signal circuits.

2. Measure the resistance between the OSS high signal circuit and the OSS low signal circuit. The resistance should be between 325-575 ohms.

⇒ | If the value is greater than 575 ohms test the OSS high signal circuit and the OSS low signal circuit for an open.

⇒ | If the value is less than 325 ohms test the OSS high signal and the OSS low signal circuits for a shorted together condition.

3. Measure the resistance of the OSS high signal circuit to ground. The resistance should be greater than 50K ohms.

⇒ | If the value is less than 50K ohms, repair the short to ground.

4. Measure the resistance between the OSS low signal circuit and ground. The resistance should be greater than 10K ohms.

⇒ | If the value is less than 10K ohms, repair the short to ground.

5. Reconnect the TCM connector. Disconnect the OSS connector. Ignition ON, test the ISS high signal circuit for a short to voltage.

⇒ | If all circuits/connections test normal, test or replace the OSS.

### Component Testing

Verify the OSS resistance is between 325-575 ohms.

⇒ | If the resistance is not within the specified range, replace the OSS.

Using the J 35616 connect the DMM between the OSS high signal and the OSS low signal circuits at the OSS connector. Raise and support the drive wheels. While rotating the drive wheels by hand ensure the AC voltage reading on the DMM is above 0.4 volts.

⇒ | If the AC voltage is not above 0.4 volts, replace the OSS.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• | Ensure that the OSS is 500 RPM or greater for 3 seconds and does not change more than 500 RPM or greater for 3 seconds.

• | Output Speed Sensor Replacement

• | Control Module References for TCM replacement, setup and programming.