P0756
DTC P0756 (4.2L)
Circuit Description
The 2-3 shift solenoid (SS) valve controls the fluid flow acting on the 2-3 shift valves. The 2-3 SS valve is a normally-open exhaust valve that is used with the 1-2 SS valve, in order to allow 4 different shifting combinations.
When the powertrain control module (PCM) detects a 4-3-3-4 shift pattern, then DTC P0756 sets. DTC P0756 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0756 2-3 Shift Solenoid Valve Performance - No First or Second Gear
Conditions for Running the DTC
- No TP sensor DTCs P0122 or P0123.
- No VSS 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 P2761.
- 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 10 percent or greater.
- The transmission fluid temperature is 20-130° C (68-266°F).
- The system voltage is 10-18 volts.
- The engine torque is 68-542 N.m (50-400 lb ft).
- The transmission output speed is 150 RPM or greater.
Conditions for Setting the DTC
DTC P0756 sets if both of the following conditions occur:
Condition 1
- The PCM commands first gear for 2 seconds.
- The estimated gear ratio is 0 to 1.4.
- All conditions are met for 1 second.
Condition 2
- The PCM commands second gear for 1 second.
- The torque converter efficiency is greater than or equal to 0.5.
- The estimated gear ratio is 0.9-1.2.
- All conditions are met for 2 seconds.
Action Taken When the DTC Sets
- The PCM illuminates the malfunction indicator lamp (MIL).
- The PCM commands third gear only.
- The PCM commands maximum line pressure.
- The PCM inhibits TCC engagement.
- The PCM freezes transmission adaptive 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 P0756 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 table Shift Speed.
- Other internal transmission failures may cause more than one shift to occur.
- Refer to the table Shift Solenoid Valve State and Gear Ratio.
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.
