4T80-E Automatic Transaxle
DTC P0756
Circuit Description
The 2-3 shift solenoid (SS) valve is a normally-open exhaust valve that, in conjunction with the 1-2 shift solenoid (SS) valve, allows four different shifting combinations. The 2-3 SS valve is attached to the lower control valve body, within the transmission.
The transmission control module (TCM) monitors the actual gear ratio, and compares the actual gear ratio with the commanded gear ratio. DTC P0756 sets under two conditions:
* A stuck ON 2-3 SS valve
* A stuck ON 2-3 shift valve
If the TCM 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 (SS) Valve Performance - No First or Second Gear
Conditions for Running the DTC
* No MAF DTCs P0101, P0102 or P0103.
* No MAP DTCs P0106, P0107 or P0108.
* No OSS DTCs P0722 or P0723.
* No AT ISS DTCs P0716 or P0717.
* No shift solenoid electrical DTCs P0973, P0974, P0976 or P0977.
* No TCC stuck ON DTC P0742.
* The engine run time is greater than 5 seconds.
* The time since the gear select lever change is 1 second.
* The transmission fluid temperature is 20-130°C (68-266°F).
* The TP angle is 8 percent or greater.
* L37: The transmission output shaft speed is 239 RPM or greater.
* The engine torque is 50-1492 N.m (37-1100 lb ft).
Conditions for Setting the DTC
The following conditions occur twice during the same trip:
* The TCM commands 1st gear and the gear ratio is 0.65:1-0.71:1 for 2 seconds.
* The TCC slip is between -20 and +8191 RPM.
* VSS for L37 is greater than 239 RPM.
* The TCM commands 2nd gear and the gear ratio is 0.95:1-1.05:1 for 3 seconds.
Action Taken When the DTC Sets
* The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
* The TCM inhibits 1st gear.
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
* The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records and the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
* The TCM stores DTC P0756 in TCM history.
Conditions for Clearing the MIL/DTC
* The ECM turns OFF the MIL after the third consecutive trip in which the TCM does not send a MIL illumination request.
* The TCM clears the DIC message when the condition no longer exists.
* A scan tool can clear the MIL/DTC.
* The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
* The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.
Diagnostic Aids
* If you clear DTC P0756, and then cannot reset DTC P0756, the following conditions may exist:
- Fluid contamination
- Plugged fluid circuits
- Restricted fluid circuits
* Refer to Shift Solenoid Valve State and Gear Ratio.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step verifies a 4-3-3-4 shift pattern.
4. This step tests for a mechanical or hydraulic condition causing the 2-3 SS valve to be stuck ON, or the circuit to be applied.
