P0751

DTC P0751

Circuit Description
The 1-2 Shift Solenoid (SS) valve is a normally-open exhaust valve that, in conjunction with the 2-3 Shift Solenoid (SS) valve, allows 4 different shifting combinations. The 1-2 SS valve is attached to the lower control valve body, within the transmission.

The Powertrain Control Module (PCM) monitors the actual gear ratio, and compares the actual gear ratio with the commanded gear ratio. DTC P0751 sets under two conditions:
^ A stuck OFF 1-2 SS valve
^ A stuck OFF 1-2 shift valve

If 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 Mass Air Flow (MAF) DTCs P0101, P0102 or P0103.
^ No Torque Converter Clutch (TCC) DTCs P2763 or P2764.
^ No Manifold Absolute Pressure (MAP) DTCs P0106, P0107 or P0108.
^ No Throttle Position (TP) DTCs P0121, P0122 or P0123.
^ No Vehicle Speed Sensor (VSS) DTCs P0502 or P0503.
^ No Automatic Transmission Input Shaft Speed (AT ISS) DTCs P0716 or P0717.
^ No Internal Mode Switch (IMS) DTCs P1820, P1822, P1823 or P1825.
^ No shift solenoid electrical DTCs P0973, P0974, P0976 or P0977.
^ The engine run time is greater than 5 seconds.
^ The IMS indicates D1, D2, D3 or D4.
^ The transmission fluid temperature is 20 - 133°C (68 - 271°F).
^ The TP angle is 7.5 percent or greater.
^ The vehicle speed is 8 km/h (5 mph) or greater.
^ The engine torque is 80 - 395 Nm (59 - 291 ft. lbs.).

Conditions for Setting the DTC
The following conditions occur twice during the same trip:
^ The PCM commands 1st gear and the gear ratio is 1.54:1 - 1.71:1, 2nd gear, for 1.5 seconds.
^ The PCM commands 4th gear and the gear ratio is 0.95:1 - 1.05:1, 3rd gear, for 4 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
^ The PCM commands maximum line pressure.
^ 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 P0751 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

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 ETC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.

Diagnostic Aids
^ If you clear DTC P0751, and then cannot reset DTC P0751, the following conditions may exist:
- Fluid contamination
- Plugged fluid circuits
- Restricted fluid circuits
- Sticking 1-2 SS
- Sticking 1-2 shift valve

^ 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 2-2-3-3 shift pattern.
4. This step tests for a mechanical or hydraulic condition causing the 1-2 SS valve to be stuck OFF, or the circuit to be released.

Steps 1-6:

DTC P0751