Pinpoint Test L : OSS (Output Shaft Speed) Sensor

Refer to Transmission Controls - 6F35 for schematic and connector information.

Normal Operation and Fault Conditions

The OSS sensor is a Hall-effect sensor that sends a signal to the PCM that indicates transmission output shaft speed. The OSS sensor is used for TCC control and shift scheduling.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
PCM P0720:00	Output Shaft Speed Sensor Circuit: No Sub Type Information	DTC P0720 sets when vehicle conditions (mainly turbine speed) indicate that OSS output should be present. Electrical failures of the OSS wiring or a failure of the sensor itself can cause this failure. Hydraulic/mechanical failure of the transmission that results in no vehicle movement in Reverse or 1st gear may also cause DTC P0720 to set. Verify the transmission operation before starting this pinpoint test.
PCM P0721:00	Output Shaft Speed Sensor Circuit Range/Performance: No Sub Type Information	Unrealistic change in the OSS sensor signal, erratic or intermittently no input.
PCM P0722:00	Output Shaft Speed Sensor Circuit No Signal: No Sub Type Information	No input from the OSS sensor.

Possible Sources

Connectors damaged or pushed-out terminals, corrosion, loose wires and missing or damaged seals
OSS sensor
PCM

L1 RETRIEVE AND RECORD ALL DTCS
- Using a diagnostic scan tool, retrieve all diagnostic trouble codes (DTCs).
Are diagnostic trouble codes (DTCs) P0720, P0721, P0722 and/or P0715, present?

Yes GO to L2

No REFER to: Diagnosis By Symptom .

L2 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR VEHICLE POWER CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect Transmission Vehicle Harness C1520A.

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

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1520A-18	Courtesy of FORD MOTOR COMPANY	Ground

Is voltage greater than 9.5 volts?

Yes

GO to L3

No	INSPECT and REPAIR the circuit. If an open circuit or a short to ground is not found, Refer to PCM Guided Routine Testing . After installing a new PCM, CARRY OUT the transmission strategy download. REFER to: Transmission Strategy Download .

L3 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR GROUND CIRCUIT

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1520A-18	Courtesy of FORD MOTOR COMPANY	C1520A-20

Is voltage greater than 9.5 volts?

Yes

GO to L4

No	INSPECT and REPAIR the circuit. If an open circuit or a short to power is not found, Refer to PCM Guided Routine Testing . After installing a new PCM, CARRY OUT the transmission strategy download. REFER to: Transmission Strategy Download .

L4 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR SIGNAL CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect PCM C1915E.

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

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1520A-19	Courtesy of FORD MOTOR COMPANY	C1915E-12

Is the resistance less than 3 ohms?

Yes

GO to L5

No	REPAIR the circuit.

L5 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1520A-19	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to L6

No	REPAIR the circuit.

L6 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR SIGNAL CIRCUIT FOR A SHORT TO POWER

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1520A-19	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit.

No	INSTALL a new OSS sensor. REFER to: Output Shaft Speed (OSS) Sensor .