VT25-E Automatic Transmission
VT25-E AUTOMATIC TRANSMISSION
DTC P0722
Circuit Description with VT25-E Automatic Transmission
The output shaft speed (OSS) sensor provides vehicle speed information to the transmission control module (TCM). The OSS is a permanent magnet generator. The OSS sensor is mounted inside the transmission, under the control valve body cover. The sensor faces the output shaft speed sensor reluctor ring. As the reluctor ring rotates, an AC voltage is induced and transmitted to the transmission control module (TCM). The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The TCM converts the AC voltage to vehicle speed. The TCM uses the output speed signal to help determine line pressure, transmission ratio control patterns and TCC apply pressure and timing.
If the TCM detects no output shaft speed when there is input shaft speed in a drive gear range, DTC P0722 sets. DTC P0722 is a type A DTC.
Conditions for Running the DTC
^ No engine speed sensor DTC P0727
^ No engine torque DTC P1779.
^ No OSS DTC P0723.
^ No ISS DTCs P0716 or P0717.
^ No transmission range switch DTCs P0705, P1756, or P1758.
^ The ignition voltage is 8 - 18 volts.
^ The engine speed is greater than 500 RPM for 5 seconds.
^ The transmission is not in PARK or NEUTRAL.
^ The throttle position angle is greater than 15 percent.
^ The engine torque is 30 - 300 Nm (22 - 221 ft. lbs.).
^ Engine torque default values are not being used.
^ The transmission input shaft speed is greater than 750 RPM.
Conditions for Setting the DTC
The transmission output shaft speed is 200 RPM or less for 5 seconds.
Action Taken When the DTC Sets
^ The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
^ The TCM moves the speed ratio towards a target ratio and then freezes ratio changes.
^ The TCM discontinues use of the closed loop ratio control algorithm. This causes the speed ratio to be defaulted and possibly not accurate. The resulting open loop control may or may not provide optimum ratio performance.
^ The TCM calculates output shaft speed from the input shaft speed sensor and the commanded speed ratio.
^ The TCM commands a line pressure increase for all operating conditions.
^ The TCM freezes main line pressure transmission adaptive functions.
^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
^ The TCM stores DTC P0722 in TCM history.
Conditions for Clearing the MIL/DTC
^ The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
^ A scan tool can clear the MIL/DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
^ The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.
Diagnostic Aids
^ Ensure the OSS sensor is properly installed in the transmission.
^ Inspect the connectors at the TCM, the transmission, and all other circuit connecting points for an intermittent condition.
^ Inspect the circuit wiring for an intermittent condition.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. The resistance measurement will not change if either the OSS high signal circuit or the OSS low signal circuit, but not both, is shorted to ground.
6. This step isolates the short between the OSS and the wiring.
12. Refer to the latest procedures for TCM reprogramming.
