OE Solutions™ 4WD Hub Locking Solenoid (600-401) by Dorman®. Restore confidence in your Four-Wheel Drive (4WD) with Dorman’s 4WD Hub Locking Solenoid. Its high-quality construction includes a durable plastic casing that won’t corrode, and that prevents water and dirt from damaging internal parts. The 4WD Hub Locking Solenoid may also be used as an Emissions Purge Solenoid in some applications.