P0756

Diagnostic Chart:

Description:

Shift Solenoid:

Circuit Description
The 2-3 Shift Solenoid Valve (2-3 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 Shift Solenoid Valve (1-2 SS Valve) in order to allow four different shifting combinations.

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

Conditions for Setting the DTC

^ No Throttle Position (TP) DTCs P0122 or P0123.
^ No Vehicle Speed Sensor Assembly (VSS Assy.) DTCs P0502 or P0503.
^ No TCC Sol. 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 Assy. DTC P0785.
^ No TFP Val. Position Sw. DTC P1810.
^ No TCC Pulse Width Modulation (PWM) Sol. Valve DTC P1860.
^ The vehicle speed is greater than 6 km/h (4 mph).
^ The gear range is D4.
^ The engine vacuum is 0-105 kPa.
^ The engine torque is 5-400 lbs ft.
^ The engine speed is greater than 450 RPM for 2 seconds.
^ Not in fuel cutoff.
^ The transmission fluid temperature is 20-130°C (68-266°F).

All of the above conditions are met three times and either of the following fail conditions occurs:

^ The solenoid is stuck ON and Conditions 2 and 3 occur three times.
^ The solenoid is stuck OFF and Conditions 1 and 2 occur three times.

Condition 1

^ The TP angle is greater than 25%.
^ First gear is commanded for 2 seconds.
^ The speed ratio is 0.7-3.0 (speed ratio is engine speed divided by output speed).
^ The transmission output speed is 400-1500 RPM.
^ The TCC slip speed is -100 to -3000 RPM.
^ All conditions met for 1.5 seconds.

Condition 2

^ The TP angle is 10-50%.
^ The TP angle is within +/-5%.
^ Third gear is commanded for 2-5.95 seconds.
^ The speed ratio in 3rd gear does not drop by more than 0.2 from the last speed ratio in 2nd gear.
^ The TCC slip speed in 3rd gear is 300 RPM greater than the last TCC slip speed in 2nd gear.
^ All conditions met for 2 seconds.

Condition 3

^ The TP angle is greater than 10%.
^ Fourth gear is commanded for 1 second.
^ The speed ratio is 1.5-3.0.
^ The TCC slip speed is 1000-4000 RPM.
^ The transmission output speed is 1400-2500 RPM.
^ All conditions met for 2 seconds.

Action Taken When the DTC Sets

^ The PCM commands 3rd gear only.
^ The PCM inhibits TCC engagement.
^ The PCM commands maximum line pressure.
^ The PCM freezes shift adapts from being updated.
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).

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

^ Verify that the transmission meets the specifications in the 4L60-E shift speed chart.
^ Other internal transmission failures may cause more than one shift to occur.

Test Description
The numbers below refer to the step numbers on the diagnostic chart.

2. This Step verifies that the scan tool commanded all shifts, and all shift solenoids responded correctly, but all the shifts did not occur.