Pinpoint Test L : OSS (Output Shaft Speed) Sensor
- Refer to OEM WIRING DIAGRAMS
for schematic and connector information.
Normal Operation and Fault Conditions
The OSS sensor is a Hall-effect type sensor that provides a signal to the PCM that changes in frequency as the rotating speed of the output shaft ring gear varies. The PCM also compares the OSS sensor signal with the TSS sensor signal to determine the gear ratio provided by the rear planetary gearset. The PCM uses the OSS sensor signal as an input for its strategies for shifts and TCC operation. The PCM also uses the OSS sensor signal for transmission fault detection and diagnostics. When the DTC P0720 is set, the module goes into failsafe mode cutting off the voltage to the transmission solenoids which revert to full line pressure, with the following gears only available, P, R, N, and 5M.
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 output. PCM P0722:00 Output Shaft Speed Sensor Circuit No Signal: No Sub Type Information No input from the OSS sensor. Possible Sources
- Wiring, terminals or connectors
- OSS sensor
- PCM
- Excessive transmission slippage (No vehicle movement in 1st or Reverse)
- L1 RETRIEVE AND RECORD ALL DTCS
- Using a diagnostic scan tool, retrieve all DTCs.
Are DTCs P0720, P0721, P0722 and/or P0715, present?
Yes For DTCs P0720, P0721 and P0722, GO to L2 For DTCs P0715 and P0720, GO to L6 No REFER to: Diagnosis By Symptom . - L2 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect Transmission Vehicle Harness C1520A.
- Disconnect PCM C1232E.
- Inspect the connectors for damaged or pushed-out terminals, corrosion, loose wires and missing or damaged seals.
- Measure:
Positive Lead Measurement / Action Negative Lead C1520A-19 C1232E-12
Is the resistance less than 3 ohms?
Yes GO to L3 No REPAIR the circuit. - L3 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
Is the resistance greater than 10, 000 ohms?
Yes REPAIR the circuit. No GO to L4 - L4 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR SIGNAL CIRCUIT FOR A SHORT TO POWER
- Ignition ON.
Is any voltage present?
Yes REPAIR the circuit. No GO to L5 - L5 CHECK THE OSS (OUTPUT SHAFT SPEED) SENSOR GROUND CIRCUIT
- Ignition OFF.
- Connect PCM C1232E.
- Ignition ON.
Is voltage less than 4.8 volts?
Yes INSPECT and REPAIR the circuit. If an open circuit is not found, Refer to PCM GUIDED ROUTINE TESTING No INSTALL a new OSS sensor. REFER to: Output Shaft Speed (OSS) Sensor . - L6 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.
Is voltage less than 9.5 volts?
Yes INSPECT and REPAIR the circuit. If an open circuit is not found, Refer to PCM GUIDED ROUTINE TESTING No CLEAR the DTC. If DTCs P0715 and/or P0720 return, Refer to PCM GUIDED ROUTINE TESTING