Shift Solenoid: Description and Operation

The ECM uses the signals from the NCO revolution sensor and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.

Then the ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect mechanical trouble of the shift solenoid valve SLU, valve body, torque converter clutch or automatic transmission (clutch, brake or gear etc.)





Shifting from 1St to 4th is done in combination with ON and OFF of the shift solenoid valves No.1 and No.2 controlled by ECM. If an open or short circuit occurs in either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the vehicle to be operated smoothly (Fail safe function).

The ECM uses signals from the NCO revolution sensor arid vehicle speed sensor to detect the actual gear position (1st, 2nd, 3rd or 4th gear).

Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical trouble of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear etc.).