P0756
Circuit Description
The Powertrain Control Module (PCM) identifies a 2-3 Shift Solenoid Valve (2-3 SS Valve) performance problem by monitoring the commanded gear versus the gear ratio.
If the PCM detects the gear ratio outside the limits for a particular commanded gear, then DTC P0756 sets. DTC P0756 is a Type A DTC.
Conditions for Setting the DTC
^ No Throttle Position (TP) DTCs P0121, P0122 or P0123 are set.
^ No Vehicle Speed (VSS) sensor DTCs P0502 or P0503 are set.
^ No IAT ISS DTCs P0716 or P0717 are set.
^ No 1-2 shift solenoid valve electrical DTC P0753 is set.
^ No 2-3 shift solenoid valve electrical DTC P0758 is set.
^ No TCC Pulse Width Modulated (PWM) Sol. DTC P1860 is set.
^ No Automatic Transmission Fluid Pressure Manual Valve Position switch (TFP Val. Position Sw.) DTC P1810 is set.
^ The engine has been running for more than 5 seconds.
^ Not in fuel shut off.
^ The Automatic Transmission Fluid Temperature is greater than 20°C (68°F).
^ The transmission is not in Park or Neutral.
^ All of the above conditions are met, and cases 1 and 2 are true for 3 seconds, twice.
^ All of the above conditions are met, and cases 3 and 4 are true for 3 seconds, twice.
Case 1
- First gear is commanded.
- The vehicle speed is greater than 11 km/h (7 mph).
- The engine torque is 70-270 N.m (50-200 lb ft).
- The throttle position is greater than 14%.
- The gear ratio is 0.65:1-0.75:1.
Case 2
- Second gear is commanded.
- The vehicle speed is greater than 11 km/h (7 mph).
- The engine torque is 70-270 N.m (50-200 lb ft).
- The throttle position is greater than 14%.
- The gear ratio is 0.95:1-1.05:1.
Case 3
- Third gear is commanded.
- The vehicle speed is greater than 11 km/h (7 mph).
- The engine torque is 70-270 N.m (50-200 lb ft).
- The throttle position is greater than 14%.
- The gear ratio is 1.52:1 to 1.62:1.
Case 4
- Fourth gear is commanded.
- The vehicle speed is 56-120 km/h (35-75 mph).
- The engine torque is 0-105 N.m (0-80 lb ft).
- The engine speed is less than 6700 RPM.
- The throttle position is 7-40%.
- The gear ratio is 1.05:1-2.97:1.
Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM commands 3rd gear.
^ The PCM commands maximum line pressure.
^ The PCM inhibits Torque Converter Clutch. The PCM disables shift adapts.
Conditions for Clearing the MIL/DTC
^ The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.
Diagnostic Aids
^ Inspect the transmission fluid for sediment.
^ Inspect the transmission filter for debris.
^ The customer may experience an engine flair or neutral in 4th gear.
^ Refer to Shift Solenoid Valve State and Gear Ratio table.
Test Description
The numbers below refer to the step numbers on the diagnostic chart.
Important: Do not drive the vehicle for an extended period of time, as additional internal damage may occur.
3. Set up data pairs on the scan tool. Drive the vehicle while commanding First gear with the scan tool.
4. This step verifies that the gear ratio indicates a Fourth gear start, and the vehicle does not achieve First gear. The list of components should be inspected and repaired, if faulty.
6. This step verifies that the gear ratio indicates Third gear and the vehicle does not achieve Second gear. The list of components should be inspected and repaired, if faulty.
8. This step verifies that the gear ratio indicates Second gear and the vehicle does not achieve Third gear. The list components should be inspected and repaired, if faulty.
10. This step verifies that the gear ratio indicates First gear and the vehicle does not achieve Fourth gear. The list of components should be inspected and repaired, if faulty.