4L60-E / 4L65-E Automatic Transmission

DTC P0751









Circuit Description with 4L60-E / 4L65-E Automatic Transmission
The 1-2 Shift Solenoid (SS) valve controls the fluid flow acting on the 1-2 and 3-4 shift valves. The 1-2 SS valve is a normally-open exhaust valve that is used with the 2-3 SS valve, in order to allow four different shifting combinations When the PCM detects a 2-2-3-3 shift pattern, then DTC P0751 sets. DTC P0751 is a type B DTC.

Conditions for Running the DTC
^ No TP sensor DTCs P0122 or P0123.
^ No VSS assembly DTCs P0502 or P0503.
^ No TCC solenoid valve DTC P0740.
^ No TCC stuck ON DTC P0742.
^ No 1-2 SS valve DTC P0753.
^ No 2-3 SS valve DTC P0758.
^ No 3-2 SS valve assembly DTC P0785.
^ No TFP manual valve position switch DTC P1810.
^ No TCC PWM solenoid valve DTC P1860.
^ The engine speed is greater than 450 RPM for 5 seconds.
^ The engine is not in fuel cutoff.
^ The gear range is D4.
^ The TP angle is greater than 10 percent.
^ The transmission fluid temperature is 20 - 130°C (68 - 266°F).
^ The system voltage is 10-18 volts.
^ The engine torque is 50-400 ft. lbs..
^ The transmission output speed is 150 RPM or greater.

Conditions for Setting the DTC
DTC P0751 sets if both of the following conditions occur twice:

Condition 1
^ The PCM commands first gear for 2 seconds.
^ The estimated gear ratio is 1.2-1.825.
^ All conditions are met for 0.5 seconds

Condition 2
^ The PCM commands fourth gear for 1 second.
^ The estimated gear ratio is 0.95-1.15.
^ All conditions are met for 6 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL).
^ The PCM commands D2 line pressure.
^ The PCM inhibits 3-2 downshift if the vehicle speed is 30 MPH or greater.
^ The PCM freezes transmission adapt functions.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
^ The PCM stores DTC P0751 in PCM history.

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 can clear the MIL/DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids
^ Verify that the transmission meets the specifications in the Shift Speed table.
^ Refer to the Shift Solenoid Valve State and Gear Ratio table.
^ Contamination may cause the TCC apply valve to intermittently stick in the valve body. Internal damage in the torque converter may cause no TCC apply.

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