Circuit description

The shift solenoid valve sl is turned ”on” and ”off” by signals from the ecm in order to control the hydraulic pressure operation, the lock–up relay valve, which then the controls operation of the lock–up clutch.

Fail safe function: if the ecm detects a malfunction, it turns the shift solenoid valve sl off.

Based on the signals from the throttle position sensor, the airflow meter and the crankshaft position sensor, the ecm sends a signal to the sl solenoid valve to regulate the hydraulic pressure and provide smoother gearshifts. The shift–solenoid valve sl responds to commands from the ecm. The valve controls the lock–up relay valve to perform the torque–converter lock–up function. If the ecm detects an open or short circuit for shift–solenoid sl, it will illuminate the mil.