P0751

DTC P0751









Circuit Description with 4L30-E Automatic Transmission
The 1-2/3 - shift solenoid valve is a normally closed shift solenoid that controls the positioning of the 1-2/3-4 shift valve. When the solenoid is closed, D32/1-2 fluid is blocked from acting on the solenoid end of the 1-2/3-4 shift valve. When the solenoid opens, D32/1-2 fluid pressure flows through the solenoid, and the valve moves against spring force.
When the TCM detects a 1-1/4-4 shift pattern, DTC P0751 will set. DTC P0751 is a type B DTC.

Conditions for Running the DTC
^ The transmission is in drive range (D).
^ No Trans Range Switch DTC P0705.
^ No Output Speed Sensor DTC P0722.
^ No 1-2/3-4 Shift Solenoid Valve DTC P0753.
^ No 2-3 Shift Solenoid Valve DTC P0758.
^ No TCM Internal - Watchdog Operation

DTC P1600
^ No TCM System Reset DTC P1625.
^ No TCC Enable Solenoid Circuit - Electrical

DTC P0743
^ No Throttle Position Signal DTC P1890. All the above conditions must be present, plus one of the following conditions:

Condition 1:
^ The commanded gear is 2nd for greater than 0.7 seconds.
^ The accelerator pedal position is greater than 30.8 percent.
^ The engine speed is 3,104-3,904 RPM.
^ The transmission output speed is greater than 992 RPM.
^ The engine torque is greater than 50 Nm (68 ft. lbs.).

Condition 2:
^ The commanded gear is 3rd for greater than 0.7 seconds.
^ The accelerator pedal position is greater than 24.9 percent.
^ The engine speed is 1,216-2,016 RPM.
^ The transmission output speed is greater than 2,016 RPM.
^ The engine torque is greater than 50 Nm (68 ft. lbs.).
^ The TCC is commanded ON.

Conditions for Setting the DTC
DTC P0751 sets if the following conditions occur two times.

Condition 1:
The TCC slip speed is between 1,400-2,000 RPM for 0.9 seconds.

Condition 2:
The TCC slip speed is between -1,000 to -100 RPM for 3.0 seconds.

Action Taken When the DTC Sets
^ The TCM flashes the sport mode lamp and sends a MIL request to the ECM on the second consecutive drive trip that the diagnostic runs and fails. The ECM then illuminates the MIL.
^ The ECM records the operating conditions in the Freeze Frame at the time of the MIL request from the TCM.
^ The transmission operates in the default mode (maximum line pressure, command 4th gear, inhibit TCC, freeze shift adapts).

Conditions for Clearing the MIL/DTC
^ The ECM turns off the MIL after three consecutive drive trips during which the TCM sends no MIL request.
^ A History DTC clears after forty consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission related diagnostic.
^ The scan tool clears the MIL/DTC.
^ The TCM cancels the DTC default mode actions when the ignition switch is Off long enough in order to power down the TCM.

Diagnostic Aids
^ Verify that the transmission meets the specifications in the Shift Speed table.
^ Other internal transmission failures may cause more than one shift to occur. Refer to Shift Solenoid Valve State and Gear Ratio.

Test Description
The number below refers to the step number on the diagnostic table.
2. This step tests that the TCM commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.