Automatic Transmission - 6F50 and 6F55

Diagnostic Routine G

Diagnostic Overview

P0720, P0721, P0722

Refer to Wiring Diagram Set 29 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

The OSS (Output Shaft Speed) sensor is a Hall-effect sensor that sends a signal to the PCM (Powertrain Control Module) that indicates transaxle output shaft speed. The OSS (Output Shaft Speed) sensor is used for TCC (Torque Converter Clutch) control and shift scheduling.

DTC Fault Trigger Conditions






Pinpoint Test

NOTE: If the scan tool is unable to communicate with the PCM (Powertrain Control Module) or access the transmission PIDs (Parameter Identifications), REFER to Computers and Control Systems Information.

1. Read and record all DTCs (Diagnostic Trouble Codes)

1. Install the scan tool and record all DTCs (Diagnostic Trouble Codes).

Were DTCs (Diagnostic Trouble Codes) P0720, P0721, P0722 and/or P0715 set?






2. Check OSS (Output Shaft Speed) sensor signal circuit for an open

1. Ignition OFF.

2. Disconnect the transaxle vehicle harness C168.

3. Disconnect the PCM (Powertrain Control Module) C175T.

4. Inspect the connectors for damaged or pushed out terminals, corrosion, loose wires and missing or damaged seals.

5. Measure the resistance of circuit RET04 (YE/OG) from the transaxle vehicle harness C168-10 to the PCM (Powertrain Control Module) C175T-25.





Is the resistance less than 5 ohms?






3. Check OSS (Output Shaft Speed) sensor signal circuit for a short to ground

1. Measure the resistance of circuit RET04 (YE/OG) from the transaxle vehicle harness C168-10 to ground.





Is the resistance greater than 10,000 ohms?






4. Check OSS (Output Shaft Speed) sensor signal circuit for a short to power

1. Ignition ON.

2. Measure for voltage between circuit RET04 (YE/OG) from the transaxle vehicle harness C168-10 to ground.





Is any voltage present?






5. Check the OSS (Output Shaft Speed) sensor ground circuit

1. Measure the voltage between circuit RET04 (YE/OG) from the transaxle vehicle harness C168-10 to the transaxle vehicle harness C168-9 circuit RET24 (BN/BU).





Is voltage less than 4.8 volts?






6. Check the solenoid body signal circuit for an open

1. Remove the main control cover. REFER to Main Control Cover .

2. Disconnect the OSS (Output Shaft Speed) sensor.

3. Measure the resistance between the transaxle internal harness connector, terminal 10 and the OSS (Output Shaft Speed) sensor connector terminal 1.





Is the resistance greater than 0.5 ohms?






7. Check OSS (Output Shaft Speed) sensor VPWR circuit for an open

1. Ignition OFF.

2. Disconnect the transaxle vehicle harness C168.

3. Inspect the connectors for damaged or pushed out terminals, corrosion, loose wires and missing or damaged seals.

4. Ignition ON.

5. Measure for voltage on circuit LE111 (VT/GN) from the transaxle vehicle harness C168-20 to ground.





Is the voltage less than 9.5 volts?