Advanced Diagnostics

DTC P0777: A/T Clutch Pressure Control Solenoid Valve B Stuck ON







General Description
A/T clutch pressure control solenoid valve B is installed in the transmission housing. A/T clutch pressure control solenoid B is operated by the powertrain control module (PCM) and converts modulated pressure to A/T clutch pressure control solenoid B pressure, which operates CPC valve B. Line pressure is modulated to clutch pressure control B pressure (CPC B pressure) by CPC valve B and the CPC valve B spring. A signal from the PCM is output to the proper gear clutch, determined by the gear schedule, to supply the proper CPC pressure according to the driving conditions. When the current from the PCM is low (OFF), A/T clutch pressure control solenoid valve B operates and the CPC valve B pressure increases. When the current from the PCM is high (ON), A/T clutch pressure control solenoid valve B turns off and the CPC valve B pressure decreases. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, an A/T clutch pressure control solenoid valve B ON failure is detected and a DTC is stored.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
The engine speed flares during 2nd - 3rd and 3rd - 4th upshifts for at least 0.5 second.

Driving Pattern
Start the engine, and accelerate the vehicle until the transmission shifts into 5th gear in the D position.

- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected during the first drive cycle, a Temporary DTC is stored in the PCM memory. If the malfunction recurs during the next (second) drive cycle, the MIL comes on and the DTC and the freeze frame data are stored.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs.

The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.