P0756
DTC P0756
Circuit Description
The 2-3 shift solenoid (SS) valve controls the fluid flow acting on the 2-3 shift valves. The 2-3 SS valve is a normally-open exhaust valve that is used with the 1-2 SS valve, in order to allow 4 different shifting combinations.
When the transmission control module (TCM) detects a 4-3-3-4 shift pattern, then DTC P0756 sets. DTC P0756 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0756 2-3 Shift Solenoid (SS) Valve Performance - No First or Second Gear
Conditions for Running the DTC
^ No OSS DTCs P0722 or P0723.
^ No TCC DTC P0742 or P0894.
^ No shift solenoid electrical DTCs P0973, P0974, P0976, or P0977.
^ The engine torque is greater than 50 Nm (37 ft. lbs.).
^ The engine run time is greater than 5 seconds.
^ The transmission fluid temperature is 20 - 130°C (68 - 266°F).
^ The throttle position is 25 percent or greater.
^ The output shaft speed is 150 RPM or greater.
Conditions for Setting the DTC
Both of the following conditions must occur twice during the same trip:
^ Fail Case 1: The TCM commands 1st gear and the resulting gear ratio is 0.69:1-1.14:1 for 1 second.
^ Fail Case 2: The TCM commands 2nd gear and the resulting gear ratio is 0.698:1-1.2:1 for 2 seconds.
Action Taken When the DTC Sets
^ The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
^ The TCM commands a soft landing to 2nd gear.
^ The TCM commands maximum line pressure.
^ The TCM freezes transmission adaptive functions.
^ The TCM inhibits 1st gear.
^ At the time of the first failure, the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record.
^ At the time of the second failure, the ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame.
^ The TCM stores DTC P0756 in TCM history.
Conditions for Clearing the 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 DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
^ The TCM cancels the default actions when the ignition is OFF long enough in order to power down the TCM.
Diagnostic Aids
^ If you clear DTC P0756, and then cannot reset DTC P0756, the following conditions may exist:
- Fluid contamination
- Plugged fluid circuits
- Restricted fluid circuits
^ Refer to Shift Solenoid Valve State and Gear Ratio.
Test Description
The number below refers to the step number on the diagnostic table.
2. This step tests that the TCM commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.
