VT25-E Automatic Transmission
VT25-E AUTOMATIC TRANSMISSION
DTC P0717
Circuit Description with VT25-E Automatic Transmission
The input shaft speed (ISS) sensor is a permanent magnet generator. The ISS sensor is mounted inside the transmission, under the control valve body cover. The sensor faces the input shaft speed sensor reluctor ring assembly. As the reluctor ring assembly 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 reluctor ring assembly increases. The TCM converts the AC voltage into a digital signal. The TCM uses the input speed signal to help determine line pressure, transmission ratio control patterns and TCC apply pressure and timing.
If the TCM detects no input shaft speed when there is vehicle speed in a drive gear range, DTC P0717 sets. DTC P0717 is a type A DTC.
Conditions for Running the DTC
^ No engine torque DTC P1779.
^ No OSS DTCs P0722 or P0723.
^ 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 selected range is not PARK or NEUTRAL.
^ The engine torque is between 30 - 300 Nm (22 - 221 ft. lbs.).
^ The transmission output shaft speed is 400 RPM or greater.
Conditions for Setting the DTC
The transmission input shaft speed is 100 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 commands maximum pressure to the input clutch.
^ The TCM calculates input shaft speed from the output shaft speed sensor and the commanded speed ratio.
^ The TCM commands a line pressure increase for all operating conditions.
^ The TCM freezes garage shift transmission adaptive functions.
^ 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 P0717 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 ISS 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 ISS high signal circuit or the ISS low signal circuit, but not both, is shorted to ground. The vehicle speed detector in the TCM and the ISS are matched in such a way that an open or a short to ground in the ISS low signal circuit will not usually cause a loss of speed signal or a DTC P0717 to set.
6. This step isolates the short between the ISS and the wiring.
12. Refer to the latest procedures for TCM reprogramming.
