Pinpoint Test E: Output Shaft Speed (OSS) Sensors

• Check to make sure the transmission harness connector is fully seated, pins are fully engaged in connector and in good condition before proceeding.
• Connect the scan tool.
• Key in ON position.
• Enter the following diagnostic mode on the scan tool: Diagnostic Data Link.
• Enter the following diagnostic mode on the scan tool: PCM.
• Select PID/Data Monitor and Record.
• Select the PID OSS.
• Does vehicle enter PID/Data Monitor and Record? 

• Yes  : GO to E2.
• No  : REPEAT procedure to ENTER PID. If vehicle did not enter PID, See INTRODUCTION - GASOLINE and/or INTRODUCTION -- 6.0L DIESEL articles for diagnosis of PCM.

• While monitoring the OSS Speed PID, drive the vehicle so that the transmission upshifts and downshifts through all gears.
• Does the OSS Speed PID increase and decrease with engine and vehicle speed? 

• Yes  : CLEAR all DTCs. ROAD TEST to verify if concern is still present. If concern is still present, REFER to DIAGNOSIS BY SYMPTOM .
• No  : If the OSS Speed PID does not increase and decrease with engine and vehicle speed, INSPECT for open or short in vehicle harness, sensor, a PCM concern, or internal hardware concern.

If the sensor signal is erratic, INSPECT for intermittent concern in the internal/external harness, sensor, or connector.

If the sensor signal is steady, GO to E3.

• Disconnect the vehicle harness connector from the OSS sensor.
• Measure the resistance between the OSS sensor pins.
  Fig 1: Measuring Resistance Between OSS Sensor Pins

  Courtesy of FORD MOTOR CO.
• Record the resistance.
• Is the resistance within 400-500 ohms at 77°F (25°C)? 

• Yes  : REFER to DIAGNOSIS BY SYMPTOM  for concern diagnosis.
• No  : INSTALL a new OSS sensor.