P0751

Diagnostic Chart:

Schematic:

Circuit Description
The 1-2, 3-4 Shift Solenoid (1-2, 3-4 SS) valve is supplied with ignition voltage by a fused circuit. The ground path is provided by the PCM, depending on the commanded state of the solenoid. When the PCM commands the solenoid OFF, a ground path is not provided and the filtered line pressure that is fed to the solenoid is exhausted When the PCM commands the solenoid ON, a ground path is provided and the exhaust port is blocked, stopping the exhaust of line pressure.

The PCM identifies a 1-2, 3-4 SS valve condition by monitoring the commanded gear versus gear ratio.

If the PCM detects a 2nd gear ratio when 1st gear is commanded and a 3rd gear ratio when 4th gear is commanded, then DTC P0751 sets. DTC P0751 is a type B DTC.

Conditions for Running the DTC
^ No TP sensor DTC P0121, P0122 or P0123.
^ No VSS DTC P0502 or P0503.
^ No AT ISS sensor DTC P0716 or P0717.
^ No transmission slipping DTC P0730.
^ No 1-2, 3-4 SS valve electrical DTC P0753.
^ No 2-3 shift SS electrical DTC P0758.
^ No TFP manual valve position switch DTC P1810.
^ No torque converter overstress DTC P1814.
^ No TCC PWM solenoid valve DTC P1860.
^ The system voltage is 8-18 volts.
^ The engine speed is greater than 500 RPM for 5 seconds and not in fuel shut off.
^ The transmission is not in PARK, NEUTRAL or REVERSE.
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The TP angle is greater than 10%.
^ The transmission fluid temperature is between 20°C (68°F) and 129°C (264°F).
^ The engine torque is 27-270 N.m (20-200 lb ft).
^ The transmission ISS is 150-8000 RPM.
^ The transmission OSS is greater than 300 RPM.
^ The time since the last gear range change is greater than 1 second.

CONDITIONS FOR SETTING THE DTC
The following conditions both occur twice in one trip:

Condition 1
The PCM commands 1st gear and the gear ratio indicates 2nd gear (1.52:1 to 1.62:1) for 1 second.

Condition 2
The PCM commands 4th gear and the gear ratio indicates 3rd gear (0.95:1 to 1.05:1) for 1 second.

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 shift adapts.
^ 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.