P0751
Diagnostic Chart:
Wiring Diagram:
CIRCUIT DESCRIPTION
The 1-2 Shift Solenoid Valve (1-2 SS Valve) controls fluid flow acting on the 1-2 shift valve and the 3-4 shift valve. The 1-2 88 Valve is a normally-open exhaust valve. Used with the 2-3 Shift Solenoid Valve (2-3 88 Valve), the 1-2 88 Valve allows four different shifting combinations.
When the PCM detects a 1-1-4-4 only or a 2-2-3-3 only shift pattern, then DTC P0751 sets. The pattern that the PCM detects depends on the mechanical failure. DTC P0751 is a type B DTC.
CONDITIONS FOR SETTING THE DTC
Failure Criteria
^ No TP DTCs P0122 or P0123
^ No Vehicle Speed Sensor (VSS) DTC P0502
^ No TCC Stuck ON DTC P0742
^ No 1-2 SS Valve DTC P0753
^ No 2-3 88 Valve DTC P0758
^ No TFP Val Position 8w DTC P1810
^ No 3-2 Shift Solenoid Valve Assembly DTC P1886
^ The gear range is D4.
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The transmission fluid temperature is between 20 and 130°C (68 and 266°F).
^ The traction control is not active.
^ All the above conditions have been met and the combination of Conditions 1,2,3, and 4 or 1,2,3, and 5 occur two consecutive times.
Condition 1
^ Commanded 1-2 shift
^ The TP angle is between 17 and 42 %.
^ The TP angle is constant within +1-3 %.
^ Vehicle speed is 848 km/h (5-30 mph).
^ Within 2.5 seconds, the engine speed in 2nd gear must be 150 RPM greater than the last speed in 1st gear.
Condition 2
^ Commanded 2-3 shift
^ The TP angle is between 17 and 32 %.
^ The TP angle is constant within +1-5 %.
^ Vehicle speed is between 32 and 72 km/h (20 and 45 mph).
^ Within 1.7 seconds, the engine speed in 3rd gear must be 75 RPM less than the last speed in 2nd gear.
Condition 3
^ Commanded 3-4 shift
^ The TP angle is between 17 and 30 %.
^ The TP angle is constant within +1-3 %.
^ The vehicle speed is between 45 and 105 km/h (28 and 65 mph).
^ Within 3 seconds, the engine speed in 4th gear must be 20 RPM greater than the last speed in 3rd gear.
Condition 4
^ Commanded 4th gear
^ The TCC is ON.
^ The TP angle is between 13 and 26 %.
^ The speed ratio is between 0.85 and 1.2 (the speed ratio is the engine speed the output speed).
^ The TCC slip speed is between 300 and 2000 RPM for greater than 4 seconds.
Condition 5
^ Commanded 4th gear
^ The TCC is ON.
^ The TP is between 13 and 26 %.
^ The Speed ratio is between 0.5 and 0.788 (the speed ratio is the engine speed the output speed).
^ The TCC slip speed is between -20 and 20 RPM for greater than 4 seconds.
ACTION TAKEN WHEN THE DTC SETS
^ D2 line pressure
^ The freeze shift adapts from being updated.
^ 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
^ Verify that the transmission meets the specifications in the 4L60-E shift speed chart.
^ More than one shift may occur because of other internal transmission failures.
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic chart.
2. This Step verifies that the TFP Valve Position Switch is functioning normally.
3. This Step verifies that the following sequence occurs:
The scan tool commands all shifts. All the shift solenoids respond properly. Not all the shifts occur.