VALVE TIMING ADJUSTMENT SYSTEM AND ELECTRONIC CONTROL DEVICE

A valve timing adjustment system includes a valve timing adjustment device, a phase lock mechanism, a hydraulic control valve, an electromagnetic drive section, and an electronic control device. When the lock pin included in the phase lock mechanism and having the tip thereof fitted into a fitting recess is removed from the fitting recess, the electronic control device performs an initial control of applying current to the electromagnetic drive section at a prescribed current value for a prescribed time to move a spool of the hydraulic control valve from an initial position. Thereafter, the electronic control device performs a gradual change control of applying current to the electromagnetic drive section while gradually increasing the current value from a current value smaller than the current value applied in the initial control but greater than 0, to remove the lock pin from the fitting recess.