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P0723




DTC P0722 or P0723

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 Instructions)provides an overview of each diagnostic category.

DTC Descriptors
DTC P0722
- Output Speed Sensor Circuit Low Voltage

DTC P0723
- Output Speed Sensor Circuit Intermittent

Diagnostic Fault Information





Typical Scan Tool Data





Circuit/System Description

The automatic transmission output speed sensor (OSS) system is a 2-wire pulse generator consisting of a speed sensor assembly, located in the case extension, and a toothed output speed sensor reluctor wheel, which is pressed onto the final drive carrier assembly. As the vehicle moves, the OSS reluctor wheel rotates. This rotation produces a variable AC signal in the pick-up coil that is proportional to vehicle speed. The transmission control module (TCM) uses this signal in order to control line pressure, torque converter clutch (TCC) apply and release, and transmission shift patterns. This sensor is also used to calculate vehicle speed, TCC slip speed, and gear ratios.

An air gap of 0.27-1.57 mm (0.011-0.062 in) is maintained between the sensor and the teeth on the speed sensor reluctor wheel. The sensor consists of a permanent magnet surrounded by a coil of wire. As the differential rotates, an AC signal is induced in the OSS. Higher vehicle speeds induce a higher frequency and voltage measurement at the sensor.

Sensor resistance should be 1500-1750 ohm when measured at 20°C (68°F). Output voltage will vary with speed from a minimum of 0.5 volts AC at 25 RPM to 200 volts AC at 1,728 RPM.

The OSS is sometimes referred to as the vehicle speed sensor (VSS).

Conditions for Running the DTC

P0722
* No TPS DTC P0120, P0121, P0122, P0123, P0220, P0221, P0222, P0223, P0225, P0226, P0227, P0228, P1120, P1121, P1122, P1125, P1280, P1281, P1282, P1283, P1285, P1286, P1287 or P1288.
* No ISS DTCs P0716 or P0717.
* No OSS DTC P0723.
* The calc. throttle position is 8 percent or more.
* The input shaft speed is 1,500-5,000 RPM.
* The TCC slip speed is -20 RPM or more.
* The TFT is -40°C (-40°F) or more.
* The engine speed is greater than 500 RPM for 5 seconds.
* The engine torque is greater than 50 Nm (37 lb ft).
* The transmission range is not PARK or NEUTRAL.
* Ignition voltage is 8.0-18.0 V.

P0723
* No ISS DTCs P0716 or P0717.
* No 1-2 SS electrical DTC P0974.
* The time since the last gear selector range change is 6 seconds or more.
* The output speed is 1,000 RPM or greater for 2 seconds.
* No transmission OSS rise 500 RPM or greater for 2 seconds.
* The ISS changes 500 RPM or less for 2 seconds.
* The engine speed is greater than 500 RPM for 5 seconds.
* The engine torque is greater than 50 Nm (37 lb ft).
* The transmission range is not PARK or NEUTRAL.
* Ignition voltage is 8.0-18.0 V.

Conditions for Setting the DTC

P0722
* The output shaft speed is 200 RPM or less for 4.5 seconds.
* The engine must be above 50 Nm (37 lb ft) in Drive range.

P0723

The output shaft speed drops greater than 1,200 RPM for 3.25 seconds.

Action Taken When the DTC Sets

* DTCs P0722 and P0723 are type B DTCs.
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
* The TCM calculates output speed based on ISS, engine speed, and commanded gear.

Conditions for Clearing the DTC

DTCs P0722 and P0723 are type B DTCs.

Diagnostic Aids

* DTC P0722 detects a very low vehicle speed signal when the vehicle has a large engine speed in a drive range, constant fault.
* DTC P0723 detects a large unrealistic drop in the vehicle speed signal in a very short period of time, intermittent fault.
* Inspect the OSS, harness, connector, and TCM pins for metallic debris and output shaft machined face for damage or misalignment.
* Inspect the 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 TCM harness connector, the 20-way connector, or a component harness connector.
* Road test the vehicle while monitoring the Transmission OSS parameter on the scan tool. The Transmission OSS parameter should vary with engine speed changes and not abruptly drop out.
* Inspect for a disconnected OSS connector.

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference

* Component Connector End Views (Connector End Views By Name)
* Inline Harness Connector End Views (Connector End Views By Number)

Description and Operation

Electronic Component Description (Electronic Component Description)for output speed sensor information
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 Relearning)for scan tool information
Special Tools

* J 38522 - Variable Signal Generator
* J 44152 - Jumper Harness - 20 Pins
* J 44257 - Main Wiring Harness Connector Remover

Circuit/System Verification

1. Operate the vehicle at 16-32 km/h (10-20 mph) while observing the transmission OSS parameter on the scan tool. The transmission OSS should vary with the vehicle speed and not drop out.
2. 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

Important: Additional DTCs may set when disconnecting the automatic transmission inline 20-way connector.


1. Ignition OFF, using the J 44257 - main wiring harness connector remover , disconnect the automatic transmission (AT) inline 20-way connector and install the J 44152 - jumper harness on the engine side of the AT inline 20-way connector.
2. Ignition ON. Engine OFF.
3. Using the GY probes J 35616-2A, test for 2.0-3.0 V between the OSS high signal circuit, OSS harness terminal B and a good ground, such as the ground terminal of the EL-49742 harness, black terminal.

• If greater than the specified value, test the OSS high signal circuit for a short to voltage, refer to Circuit Testing (Circuit Testing). If all circuits and connections test normal, test the TCM.
• If less than the specified value, test the OSS high signal circuit for an open/high resistance, short to ground, short to voltage or short to OSS low signal circuit, refer to Circuit Testing (Circuit Testing). If all circuits and connections test normal, test the TCM.

• If 2.0-3.0 V.

4. Using the GY probes J 35616-2A, test for 2.0-3.0 V between the OSS low signal circuit, OSS harness terminal A, and a good ground, such as the ground terminal of the EL-49742 harness, black terminal.

• If greater than the specified value, test the OSS low signal circuit for a short to voltage, refer to Circuit Testing (Circuit Testing). If all circuits and connections test normal, test the TCM.
• If less than the specified value, test the OSS low signal circuit for an open/high resistance, short to ground, short to voltage or short to OSS high signal circuit, refer to Circuit Testing (Circuit Testing). If all circuits and connections test normal, test the TCM.

• If 2.0-3.0 V.

5. Using the L-BU probes J 35616-64B, test for greater than 10K ohm between the OSS high signal circuit, jumper harness terminal B, and all other circuits of the J 44152 - jumper harness.

• If less than the specified value, test the affected circuits for a shorted together condition. If all circuits and connections test normal, test the TCM.

• If greater than 10K ohm.

6. Using the L-BU probes J 35616-64B, test for greater than 10K ohm between the OSS low signal circuit, jumper harness terminal A, and all other circuits of the J 44152 - jumper harness.

• If less than the specified value, test the affected circuits for a shorted together condition. If all circuits and connections test normal, test the TCM.

• If greater than 10K ohm.

7. If all circuits test normal, test the OSS for proper operation.

Alternate Method
1. Ignition OFF. Disconnect the connector at the TCM.

Note: When test probing TCM harness terminals, it is imperative to use the proper test probe from the most current version of the J 35616 GM terminal test kit. Use of the brown J 35616-6 (1.00 mm) PCM probe in a 0.64 mm terminal will deform the terminal, resulting in intermittent open conditions. The correct probe for TCM harnesses is the light blue J 35616-64B probe.

2. Using the light blue probe J 35616-64B test for greater than 250 ohm between the OSS high signal circuit, TCM harness terminal 41, and a good ground, such as the ground terminal of the EL-49742 harness, black terminal.

• If less than the specified value, test the affected circuit for a short to ground. If all circuits and connections test normal, test the OSS.

• If greater than 250 ohm.

3. Using the light blue probe J 35616-64B test for greater than 250 ohm between the OSS low signal circuit, TCM harness terminal 16, and a good ground, such as the ground terminal of the EL-49742 harness, black terminal.

• If less than the specified value, test the affected circuit for a short to ground. If all circuits and connections test normal, test the OSS.

• If greater than 250 ohm.

4. Disconnect the connector at the OSS.
5. Using a 5A fused jumper wire and the light blue probes J 35616-64B, test for greater than 10K ohm between the OSS high signal circuit, TCM harness terminal 41, and all other circuits of the TCM harness.

• If less than the specified value, test the affected circuits for being shorted together. If all circuits and connections test normal, test the OSS.

• If greater than 10K ohm.

6. Using a 5A fused jumper wire and the light blue probes J 35616-64B, test for greater than 10K ohm between the OSS low signal circuit TCM harness X1 terminal 16 and all other circuits of TCM harness.

• If less than the specified value, test the affected circuits for being shorted together. If all circuits and connections test normal, test the OSS.

• If greater than 10K ohm.

7. Using the light blue probe J 35616-64B and the grey probe J 35616-2A, test the OSS high signal circuit for less than 10 ohm between TCM harness terminal 41 and OSS harness terminal B.

• If greater than the specified value, test the OSS high signal circuit for an open/high resistance. If all circuits and connections test normal, test the OSS.

• If greater than 10 ohm.

8. Using the light blue probe J 35616-64B and the grey probe J 35616-2A, test the OSS low signal circuit for less than 10 ohm between TCM harness X1 terminal 16 and OSS harness terminal A.

• If greater than the specified value, test the OSS low signal circuit for an open/high resistance. If all circuits and connections test normal, test the OSS.

• If greater than 10 ohm.

9. If all circuits and connections test normal, test the TCM.

Component Testing

OSS
1. Ignition OFF.
2. Disconnect the OSS, also known as the vehicle speed sensor (VSS).
3. Using the GY probes J 35616-3, test for 1500-1900 ohm between the OSS high signal circuit, OSS terminal B, and the OSS low signal circuit, OSS terminal A. Refer to the Component Resistance (Component Resistance) chart.

• If greater than the specified value, replace the OSS.
• If less than the specified value, replace the OSS.

• If 1500-1900 ohm.

4. Using the GY probes J 35616-3, test for greater than 10M ohm between the OSS high signal circuit, terminal B and the transmission case.

• If less than the specified value, replace the OSS.

• If greater than 10M ohm.

5. Using the GY probes J 35616-3, test for greater than 10M ohm between the OSS low signal circuit, terminal A and the transmission case.

• If less than the specified value, replace the OSS.

• If greater than 10M ohm.

6. Engage parking brake. Block the rear wheels. Sufficiently support the vehicle to safely place the transmission in neutral. Raise and support the passenger's side front wheel.
7. While rotating the raised wheel hand, test for greater than 0.15V AC, between the OSS high signal circuit, OSS pin B, and the OSS low signal circuit, OSS pin A.

• If the AC voltage is less than 0.15 V, replace the OSS.

• If the AC voltage is greater than 0.15 V.

8. If all circuits and connections test normal, test the TCM.

TCM
1. Ignition OFF, disconnect the OSS connector.
2. Ignition ON. Engine OFF.
3. Using the GY probes J 35616-2A, connect the J 38522 - variable signal generator between the OSS high signal circuit, OSS harness terminal B and the OSS low signal circuit, OSS harness terminal A. Set signal to 30V. Frequency to 30 Hz. Duty cycle to 50 percent.
4. While monitoring the Transmission OSS parameter on the scan tool vary the frequency. As the frequency increases the OSS parameter should increase. As the frequency decreases the OSS parameter should decrease. The J 38522 - variable signal generator when set to 30V will vary the OSS parameter RPM from about 180 RPM at 30 Hz to 8200 RPM at 5000 HZ. Refer to OSS parameter/RPM in the Typical Readings Using the Variable Signal Generator J 38522 chart below.

• If the OSS parameter does not perform as described, test the affected circuits for an open/high resistance condition, short to ground or short to voltage, refer to Circuit Testing (Circuit Testing). If all circuits and connections test normal replace the TCM.

• If the OSS parameter performs as described.

5. If all circuits and connections test normal, test the OSS.





Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.

* Vehicle Speed Sensor Replacement (4T45-E - Automatic Transmission)
* Control Module References (Programming and Relearning)for TCM replacement, setup, and programming

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