This solenoid valve coil generates the magnetic field that shifts the spool in a hydraulic control valve. It is mounted on the valve body within the hydraulic system of the host vehicle. When energized, the coil pulls the armature, which moves the spool to direct oil flow to a specific actuator or circuit. A shorted or open coil prevents the valve from shifting, causing the affected function to remain stuck in one position or fail to operate entirely. The original coil is wound to match the resistance and current draw of the original valve assembly, ensuring the magnetic force is sufficient to shift the spool under full system pressure.