P0756

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The 2-3 Shift Solenoid Valve (2-3 SS Valve) controls the fluid flow acting on the 2-3 shift valves. The solenoid is a normally-open exhaust valve. The combination of the 2-3 SS Valve and the 1-2 Shift Solenoid Valve allows four different shift combinations.

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

Conditions for Setting the DTC
- No Throttle Position Sensor (TPS) DTCs P0122 or P0123
- No Vehicle speed Sensor (VSS) DTCs P0502 or P0503
- No Torque Converter Clutch (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 Valve Position Switch DTC P1810
- No CC PWM Sol. Valve DTC P1860
- The vehicle speed is greater than 6 km/h (4 mph).
- The gear range is D4.
- The engine speed is greater than 400 RPM for 5 seconds and not in fuel cutoff.
- The Transmission Fluid Temperature (TFT) is 20-130°C (68-266°F).
- The engine vacuum is 0-105 kPa.
- The engine torque is 6-542 N.m (5-400 lb ft). All the above conditions are met and one of the following combinations occurs:
- Cases 1 and 3 occur three consecutive times.
- Cases 2 and 3 occur three consecutive times.
- Cases 3 and 4 occur three consecutive times.
- Any combination of (Cases 1 and 3) and (Cases 2 and 3) occur three consecutive times.

Case 1
- First gear is commanded for 2 seconds, or more.
- The TP angle is 15% or more.
- The TCC slip is -3000 to 0 RPM.
- The speed ratio is 0.65-3.0 (Speed ration is engine speed divided by Output Speed).
- The output speed is 400-1500 RPM.
- All conditions are met for greater than 1.5 seconds.

Case 2
- Second gear is commanded for 409.5 seconds or more.
- The TCC slip is 0 RPM.
- The TP angle is greater than 99.9%.
- The output speed is 8191.75 RPM.
- The speed ratio is 0 (speed ratio is engine speed + output speed).
- All conditions are met for greater than 409.5 seconds.

Case 3
- Third gear is commanded for 2.54.4 seconds. The TP angle is 13-50%.
- The TP angle is constant within +/- 5%.
- The speed ratio does not decrease more than 0.35 from the last slip in second gear.
- The TCC slip in third gear is greater than the last slip in second gear plus 600 RPM.
- All conditions are met for greater than 1 second.

Case 4
- Fourth gear is commanded for greater than 1 second.
- The TCC slip speed is 1000-4000 RPM.
- The output speed is 1400-2500 RPM.
- The TP angle is greater than 10%.
- The speed ratio is 1.68-3.3 (speed ration is the engine speed + output speed).
- All conditions are met for greater than 1 second.

Action Taken When the DTC Sets
- The PCM freezes shift adapts from being updated.
- The PCM defaults the transmission to 3rd gear.
- The PCM commands maximum line pressure.
- The PCM inhibits TCC engagement.
- 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 Shift Speed table.
- Refer to Shift Solenoid Valve State and Gear Ratio.
- 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 TFP Valve Position Switch is functioning normally.
3. This step tests for a selected gear ratio vs a ratio not obtainable under normal driving conditions.