P0756

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The 2-3 Shift Solenoid Valve (2-3 SS Valve) controls transmission fluid pressure on the 2-3 Shift Valve. Circuits 439/839 provide ignition voltage to the solenoid. When the PCM commands the solenoid OFF, filtered line pressure is exhausted at the solenoid. When the PCM commands the solenoid ON, the Output Driver Module (ODM) within the Powertrain Control Module (PCM) provides a ground which energizes the solenoid. This causes the shift valve to move, closing the exhaust port and allowing line pressure to the hydraulic passage.

The PCM monitors the commanded gear and the speed ratio to identify a malfunction in the 2-3 Shift Solenoid Valve.

When the PCM detects a 1-2-2-1 or a 4-3-3-4 shift pattern, 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 (VSS) DTCs P0502 or P0503.

^ No Torque Converter Clutch (TCC) solenoid Stuck On DTC P0742.

^ No solenoid electrical DTCs P0740, P0753, P0758 or P1860.

^ The engine speed is greater than 500 RPM for 5 seconds.

^ Not in fuel shut off.

^ The vehicle speed is greater than 26 km/h (16 mph).

^ Transmission Fluid Temperature is 20-130°C (66-266°F).

^ The transmission range indicates D4.

^ All of the above must occur and one of the following fail conditions must occur:

^ Fail case 3 and 4 must occur three times (stuck on).

^ Fail case 1 and 3 or fail case 2 and 3 must occur three times (stuck off).

Case 1

^ The PCM commands first gear for more than 1.5 seconds.

^ The TCC slip speed is -4064 to -200 RPM.

^ Output speed is 900-1600 RPM.

^ The speed ratio is 0.62.3.

^ Throttle position is more than 35%.

^ Engine torque is 54-271 N.m (40-200 ft lbs).

^ All of the above occurs for more than 1.5 seconds.

Case 2

^ The PCM commands second gear for more than 2 seconds.

^ The TCC slip speed is -4064 to 0 RPM.

^ Output speed is 1000-2100 RPM.

^ The speed ratio is 0.97-1.45.

^ Throttle position is more than 18%.

^ Engine torque is 54-271 N.m (40-200 ft lbs).

^ All of the above occurs for more than 2.0 seconds.

Case 3

^ The PCM commands third gear for 2.5-7.5 seconds.

^ The TCC slip speed is 600 RPM more than the last slip speed in second gear.

^ The speed ratio is not 0.4 less than the last speed ratio in second gear.

^ Throttle position is 14-45% and constant by 7%.

^ Engine torque is 54-271 N.m (40-200 ft lbs).

^ All of the above occurs for more than 2.0 seconds.

Case 4

^ The PCM commands fourth gear for more than 1.0 second.

^ The TCC slip speed is 1600-6000 RPM.

^ Output speed is 1500-2800.

^ The speed ratio is 2-4.

^ Throttle position is more than 10%.

^ All of the above occurs for more than 1.5 seconds.

Action Taken When the DTC Sets

^ The PCM illuminates the Malfunction Indicator Lamp (MIL).

^ Transmission defaults to 3rd gear. The PCM inhibits TCC.

Conditions for Clearing the MIL/DTC

The PCM turns OFF the MIL after three consecutive trips 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

^ Check for PRNDL DTC P0705. DTC P0705 affects transmission operation. This may set DTC P0756.

^ Inspect the transmission fluid for sediment.

^ Inspect the transmission filter for debris.

^ Ensure that the scan tool commanded gear has correct solenoid states and ratio. Refer to Shift Solenoid Valve State and Gear Ratio table.

Test Description

The number below refers to the step number on the diagnostic table.

3. Once the DTC is verified, replace the 2-3 shift solenoid.