Automatic transmissions use fluid pressure to activate transmission shifts. This performs gear shifts, achieves Torque Converter Clutch (TCC) lock-up, and smoothes shift points for better drivability. To obtain line pressure for these functions, pressure control solenoids are used.
According to the manufacturer, the pressure control solenoid “B”, contributes to gear shift control and locks the TCC. It does this by regulating the fluid pressure of the belts and clutches. This solenoid is electronically controlled by the PCM (Powertrain Control Module) or TCM (Transmission Control Module).
When the P0777 OBDII fault code is displayed, it is because the pressure control solenoid “B” is stuck.
The factors for which the P0777 OBD2 error code is stored are:
The transmission fluid may be contaminated or the transmission fluid level may be excessively low.
The pressure solenoid "B" could be faulty.
Perhaps the pressure solenoid "B" harness is shorted.
Possible solutions of the DTC code P0777 Generic
To troubleshoot the DTC P0777 OBDII code you must do the following:
Verify that the transmission fluid level is necessary to achieve a good operation of the system. Make sure there are no fluid leaks or elements that contaminate the fluid. Replace the fluid if necessary.
Inspect the wiring leading to pressure solenoid "B" and verify that all electrical components are in good condition. Burned, frayed wires or corroded connectors should be repaired or replaced.
Perform voltage checks based on the manufacturer's guidelines. Verify that the system wiring has the proper resistance level. Repair as required.