Pinpoint Test C: OSS Sensors

WARNING: This page is about a different car, the 2010 Mercury Milan, 2010 Lincoln MKZ, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Refer to the Transaxle Vehicle Harness Connector illustrations within the TRANSAXLE CONNECTOR LAYOUTS procedure.

C1 ELECTRONIC DIAGNOSTICS
- Check to make sure the Transmission Control Module (TCM) connector is fully seated, pins are fully engaged in the connector and in good condition before proceeding.
- Connect the scan tool.
- Ignition ON.
- Monitor the PID for the Output Shaft Speed (OSS) sensor.
- Monitor and record speed.
- Does the OSS match the vehicle speed?
- Yes : CLEAR all DTCs. ROAD TEST to verify concern is not present. Concern could be intermittent. If concern is still present or reappears, GO to C2.
- No: GO to C2.
C2 CHECK OSS SENSOR RESISTANCE
- Remove the TCM .
- Measure the resistance at the transaxle bulkhead electrical connector between pin 19 and 20.
  
  Fig 1: Measuring Resistance At Transaxle Bulkhead Electrical Connector Between Pin 19 And 20
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes: CLEAR all DTCs. ROAD TEST to verify concern is not present. Concern could be intermittent. If concern is still present or reappears, GO to C3.
- No: GO to C4.
C3 CHECK OSS SENSOR FOR SHORT TO GROUND
- Remove the TCM .
- Measure the resistance at the transaxle bulkhead electrical connector between pin 19 and ground.
  
  Fig 2: Measuring Resistance At Transaxle Bulkhead Electrical Connector Between Pin 19 & Ground
  Courtesy of FORD MOTOR CO.
- Measure the resistance at the transaxle bulkhead electrical connector between pin 20 and ground.
  
  Fig 3: Measuring Resistance At Transaxle Bulkhead Electrical Connector Between Pin 20 & Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes: INSTALL a new TCM and REFLASH to the latest level calibration. CLEAR all DTCs. ROAD TEST to verify concern is not present. Concern could be intermittent. If concern is still present or reappears, GO to C4.
- No: GO to C4.
C4 CHECK OSS SENSOR RESISTANCE
- Remove the transaxle side cover.
- Measure the resistance at the speed sensor electrical connector between pin 1 and 2.
  
  Fig 4: Measuring Resistance At Speed Sensor Electrical Connector Between Pin 1 & 2
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes: INSTALL a new internal harness.
- No: INSTALL a new transaxle assembly.