P0756

Schematic:

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 four different shifting combinations.

When the PCM detects a 1-2-2-1 or a 4-3-3-4 shift pattern, depending on the state of the mechanical failure, then DTC P0756 sets. DTC P0756 is a type A DTC.

CONDITIONS FOR RUNNING THE DTC
^ No TP sensor DTCs P0122 or P0123.
^ No VSS assembly DTCs P0502 or P0503.
^ No TCC solenoid valve DTC P0740.
^ No TCC stuck ON DTC P0742.
^ No 1-2 SS valve DTC P0753.
^ No 2-3 SS valve DTC P0758.
^ No 3-2 SS valve assembly DTC P0785.
^ No TFP manual valve position switch DTC P1810.
^ No TCC PWM solenoid valve DTC P1860.
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The engine vacuum is 0-105 kPa.
^ The engine torque is 40-400 lb ft.
^ The TP angle is 10-50%.
^ The TP angle is constant within 7%.
^ The engine is not in fuel cutoff.
^ The gear range is D4.
^ The transmission fluid temperature is 20-130°C (68-266°F).
^ The PCM commands a 1-2, 2-3 and 3-4 shift.

CONDITIONS FOR SETTING THE DTC
DTC P0756 sets if the following conditions occur three times:
^ Third gear is commanded for 2 to 6 seconds.
^ The speed ratio in 3rd gear does not drop more than 0.35 from the last speed ratio in 2nd gear (speed ratio is engine speed divided by transmission output speed).
^ The TCC slip speed in 3rd gear remains 300 RPM higher than the last TCC slip speed in 2nd gear.

All of the above conditions are met for 1.5 seconds and one of the following conditions occurs:

Condition 1
^ First gear is commanded for 2 seconds.
^ The TP angle is greater than 25%.
^ The transmission output speed is 400-1500 RPM.
^ The speed ratio is 0.7 to 3.0.
^ The TCC slip speed is -3000 to -100 RPM for 1.5 seconds.

Condition 2
^ The engine torque is 0-400 lb ft. Fourth gear is commanded for 1 second.
^ The transmission output speed is 1400-3000 RPM.
^ The speed ratio is 1.68 to 3.5.
^ The TCC slip speed is 1000 to 4000 RPM for 1 second.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM commands 3rd gear only.
^ The PCM commands maximum line pressure.
^ The PCM inhibits TCC engagement.
^ The PCM freezes shift adapts from being updated.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
^ The PCM stores DTC P0756 in PCM history.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ A scan tool can clear the MIL/DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS
^ Verify that the transmission meets the specifications in the Shift Speed table.
^ Ensure that the proper transmission oil filter assembly is being used in conjunction with the applicable transmission oil pan.
^ Other internal transmission failures may cause more than one shift to occur.
^ Refer to the Shift Solenoid Valve State and Gear Ratio table.

Diagnostic Chart:

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that the PCM commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.