Pinpoint Test E: Output Shaft Speed (OSS) Sensors

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Refer to the OUTPUT SHAFT SPEED (OSS) SENSOR HARNESS CONNECTOR illustration preceding these pinpoint tests.

E1 ELECTRONIC DIAGNOSTICS
- With the vehicle in NEUTRAL, position it on a hoist. Refer to JACKING & LIFTING .
- Check to make sure the transmission harness connector is fully seated, pins are fully engaged in connector and in good condition before proceeding.
- Install Diagnostic 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, REFER to the INTRODUCTION - GASOLINE article for diagnosis of PCM. If equipped with fire suppression system, GO to E4.
E2 DRIVE CYCLE TEST
- 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 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 . If equipped with fire suppression system, GO to E4.

No : If the OSS Speed PID does not increase and decrease with vehicle speed, INSPECT for open or short in vehicle harness, sensor, a PCM concern or internal hardware concern. GO to E3.

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

If the sensor signal is consistent/unchanging output, GO to E3.
E3 CHECK THE PCM HARNESS FOR OPENS
- Disconnect: PCM.
- Disconnect: OSS Sensor.
- Measure the resistance between PCM pin 14 and OSS connector pin 2 harness side.
  
  Fig 1: Measuring Resistance Between PCM Pin 14 And OSS Connector Pin 2 Harness Side
  Courtesy of FORD MOTOR CO.
- Measure the resistance between PCM pin 43 and OSS connector pin 1 harness side.
  
  Fig 2: Measuring Resistance Between PCM Pin 43 And OSS Connector Pin 1 Harness Side
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to E4.

No : REPAIR the circuit. TEST the system for normal operation.
E4 CHECK THE PCM HARNESS FOR SHORT TO GROUND
- Disconnect: PCM.
- Disconnect: OSS Sensor.
- Measure the resistance between PCM pin 14 and chassis ground.
  
  Fig 3: Measuring Resistance Between PCM Pin 14 And Chassis Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to E5.

No : REPAIR the circuit. TEST the system for normal operation.
E5 CHECK RESISTANCE OF OSS SENSOR
- Disconnect the vehicle harness connector from the OSS sensor.
- Measure the resistance between the OSS sensor pins.
  
  Fig 4: Measuring Resistance Between OSS Sensor Pins
  Courtesy of FORD MOTOR CO.
- Is the resistance between 400-500 ohms at 25°C (77°F)?
Yes : REFER to DIAGNOSIS BY SYMPTOM INDEX for concern diagnosis. If equipped with fire suppression system, GO to E6.

No : INSTALL a new OSS sensor. If equipped with fire suppression system, GO to E6.
E6 REPOWER THE FIRE SUPPRESSION SYSTEM
- Verify that the fire suppression system is repowered. Refer to FIRE SUPPRESSION SYSTEM .
- Is the fire suppression system repowered?
Yes : Fire suppression system repowering is complete.

No : REFER to FIRE SUPPRESSION SYSTEM for fire suppression system depowering and repowering procedure.