P0756

Diagnostic Chart:

Circuit Description

The Powertrain Control Module (PCM) monitors the commanded gear and speed ratio in order to identify a 2-3 Shift Solenoid Valve (2-3 SS Valve) problem. If the PCM detects a gear other than 1st gear when 1st gear is commanded, then DTC P0756 sets. If the PCM detects 1st gear when 4th gear is commanded, 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 TCC Solenoid DTCs P0740 or P0742.

^ No 1-2 Solenoid Electrical DTC P0753.

^ No 2-3 Solenoid Electrical DTC P0758.

^ No TCC PWM Solenoid Electrical DTC P1860.

^ The Transmission Fluid Temperature (TFT) is 20 - 130°C (68 - 266°F).

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

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

^ The engine is not in fuel shut off.

^ All the above, and one of the following conditions must be true

- Fail cases 3 and 4 occur twice.

- Fail cases 1 and 3 occur three times.

- Fail cases 2 and 3 occur three times.

Case 1

^ 1st gear is commanded for more than 2 seconds.

^ TCC slip speed is -4064 to -300.

^ The output speed is 900-1600 RPM

^ The speed ratio is 0.6-2.3.

^ The throttle position is more than 35%.

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

Case 2

^ 2nd gear is commanded for more than 2 seconds.

^ The TCC slip speed is -1000 to 100 RPM.

^ The output speed is 1000-2100 RPM.

^ The speed ration is 0.97-1.45.

^ The throttle position is more than 18%.

^ All of the above occurs for more than 2 seconds.

Case 3

^ 3rd gear is commanded for 2.5-7.5 seconds.

^ The TCC slip speed is 600 RPM more than the slip speed in 2nd gear.

^ The speed ratio is not 0.4 less than the speed ratio in 2nd gear.

^ The throttle position is 14M5% and constant by 7%.

^ All the above occurs for more than 2 seconds.

Case 4

^ 4th gear is commanded for more than 1 second.

^ The TCC slip speed is 1600-6000 RPM.

^ The output speed is 1500-2800 RPM.

^ The speed ratio is 2 - 4.

^ The throttle position is more than 10%

^ All of the above for more than 1.5 seconds

Action Taken When the DTC Sets

^ The PCM defaults the transmission to 3rd gear.

^ 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

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

^ Inspect the transmission fluid for sediment.

^ Inspect the transmission filter for debris.

^ 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.