P0756

Circuit Description

The 2-3 shift solenoid valve controls the fluid acting on the 2-3 shift valve. The PCM commands the solenoid ON or OFF by controlling the ground on the circuit. When the solenoid is OFF, line pressure exhausts through the solenoid valve, allowing the 2-3 shift valve to be held by spring pressure in the third and fourth gear position. When the solenoid is ON, the exhaust flow is blocked, allowing line pressure to the 2-3 shift valve. This moves the 2-3 shift valve to the first and second gear position.

When the PCM detects a 1-2-2-1 or a 4-3-3-4 shift pattern under test conditions, without an electrical malfunction, then DTC P0756 sets. DTC P0756 is a type A DTC.

Conditions for Running the DTC

^ No TP DTCs P0122 or P0123.
^ No VSS DTCs P0502 or P0503.
^ No 1-2 solenoid electrical DTC P0753.
^ No 2-3 solenoid electrical DTC P0758.
^ No TCC solenoid DTCs P0740 or P0742.
^ No TCC PWM solenoid electrical DTC P1860.
^ The engine speed is greater than 500 RPM for 5 seconds.
^ Not in fuel shut off.
^ The transmission range selector position is D4.
^ The vehicle speed is greater than 26 km/h (16 mph).
^ TFT is 20-130°C (68-266°F).

Conditions for Setting the DTC

DTC P0756 sets if one of the following conditions is true:

^ Fail case 3 and 4 (stuck on) occurs twice.
^ Fail case 1 and 3 or fail case 2 and 3 (stuck off) occurs twice.

Failure Criteria

Case 1
^ Output speed is 900-1,600 RPM.
^ The speed ratio is 0.7-2.6.
^ Throttle position is more than 35%.
^ Engine torque is 54-271 N.m (40-200 ft lbs).
^ The PCM commands first gear for more than 1.5 seconds.
^ The TCC slip speed is -4,064 to -200 RPM.
^ All of the above occurs for more than 1.5 seconds.

Case 2
^ Output speed is 1,000-2,100 RPM.
^ The speed ratio is 1.09-1.6.
^ Throttle position is more than 18%.
^ Engine torque is 54-271 N.m (40-200 ft lbs).
^ The PCM commands second gear for more than 2 seconds.
^ The TCC slip speed is -4,064 to 0 RPM.
^ All of the above occurs for more than 2.0 seconds.

Case 3
^ Throttle position is 14-55% and constant within + or -7%.
^ Engine torque is 54-271 N.m (40-200 ft lbs).
^ The PCM commands third gear for 2.5-7.5 seconds.
^ The TCC slip speed is at least 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.
^ All of the above occurs for more than 2.0 seconds.

Case 4
^ The PCM commands fourth gear for more than 1.0 second.
^ Throttle position is more than 10%.
^ Output speed is 1,500-2,800.
^ The speed ratio is 2-4.
^ The TCC slip speed is 1,600-6,000 RPM.
^ 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).
^ The PCM commands third gear only.
^ The PCM inhibits TCC operation.

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 clears the DTC from PCM history.
^ The PCM clears the DTC from the PCM history if the vehicle completes 40 consecutive warm-up cycles without an emission related diagnostic fault occurring.
^ 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

^ Inspect the transmission fluid and filter for sediment or debris.
^ Ensure that the scan tool commanded gear has correct solenoid states and ratio.

Test Description

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

3. Verify the DTC and inspect shift solenoid and shift valve for sediment or missing O-ring.
4. If the problem is not corrected in step 3, replace the 2-3 shift solenoid.