P0751

Diagnostic Chart:

Schematic:

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

The 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

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 DTCs P0121, P0122, or P0123.
^ No VSS DTCs P0502 or P0503.
^ No AT ISS DTCs P0716 or P0717.
^ No shift solenoid electrical DTCs P0753 or P0758.
^ No TFP manual valve position switch DTC P1810.
^ The engine is running.
^ The TFP manual valve position switch is not indicating PARK, REVERSE, or NEUTRAL.
^ The transmission fluid temperature is greater than 21°C (70°F).
^ The TP is greater than 8%.
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The engine torque is greater than 27 N.m (20 lb ft).

CONDITIONS FOR SETTING THE DTC
^ The PCM commands 1st gear and the gear ratio is 1.54:1-1.71:1 (2nd gear) for 2 seconds.
^ The PCM commands 4th gear and the gear ratio is 0.91:1-1.07:1 (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 inhibits TCC engagement.
^ The PCM inhibits 3-2 downshifts above 56 km/h (35 mph).
^ The PCM freezes shift adapts from being updated.
^ 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 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
^ If you clear DTC P0751, and then cannot reset DTC P0751, inspect for the following conditions:
- Fluid contamination
- Plugged fluid circuits
- Restricted fluid circuits
^ Inspect for a stuck TP sensor.
^ 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.