P0756

Diagnostic Chart:

Wiring Diagram:

Description:

Circuit Description

The 2-3 Shift Solenoid Valve (2-3 SS Valve) is a normally-open exhaust valve that, in conjunction with the 1-2 Shift Solenoid Valve (1-2 SS Valve), allows 4 different shifting combinations. The 2-3 SS Valve is attached to the control valve body, within the transmission.

The Powertrain Control Module (PCM) monitors the actual gear ratio, and compares the actual gear ratio with the commanded gear ratio. DTC P0756 sets under four conditions:

^ A stuck ON 2-3 SS Valve

^ A stuck OFF 2-3 SS Valve

^ A stuck ON 2-3 shift valve

^ A stuck OFF 2-3 shift valve

When the PCM detects an actual gear ratio that does not agree with the commanded gear, then DTC P0756 sets. DTC P0756 is a type A DTC.

Conditions for Setting the DTC

^ No Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) DTC P1810.

^ No Throttle position (TP) Sensor DTCs P0121, P0122, or P0123.

^ No Vehicle Speed (VSS) sensor DTCs P0502 or P0503.

^ No Input Speed Sensor DTCs P0716 or P0717.

^ No 1-2 shift solenoid electrical DTC P0753.

^ No 2-3 shift solenoid electrical DTC P0758.

^ No engine torque DTC P1644.

^ The engine is running.

^ The TFP Val. Position Sw. indicates D4, D3, D2, or D1.

^ The vehicle speed is greater than 8 km/h (5 mph).

^ The TP is greater than 8%.

^ Engine torque is 19-377N.m (15-300 lb. ft).

^ The MAP is greater than 20 kPa.

^ The transmission fluid temperature is greater than -10°C (14°F).

^ All of the above conditions are true, and any one of the following fail cases occurs twice:

Case 1

^ The PCM commands 1st gear and the gear ratio is 1:0.67-1:0.72 (4th gear) for 2 seconds.

^ The PCM commands 2nd gear and the gear ratio is 1:0.93-1:1.05 (3rd gear) for 5 seconds.

Case 2

^ The PCM commands 3rd gear and the gear ratio is 1:1.54-1:1.71 (2nd gear) for 5 seconds.

^ The PCM commands 4th gear and the gear ratio is 1:2.87-1:3.13 (1st gear) for 5 seconds.

Action Taken When the DTC Sets

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

^ The PCM freezes shift adapts from being updated.

^ The PCM inhibits TCC engagement.

^ The PCM commands maximum line pressure.

^ The PCM commands an immediate landing to 2nd gear.

^ DTC P0756 is stored in the PCM history.

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

^ If you clear DTC P0756, and then cannot reset DTC P0756, inspect for the following conditions:

- Fluid contamination

- Plugged oil circuits

- Restricted oil circuits

Test Description

The numbers below refer to the Step numbers on the diagnostic table.

3. This Step verifies that the gear ratio is correct for the commanded gear. -

5. This Step tests for a mechanical or hydraulic problem causing the 2-3 SS valve to be stuck OFF, or the circuit to be released.

7. This Step tests for a mechanical or hydraulic problem causing the 2-3 SS valve to be stuck ON, or the circuit to be applied.