Buy OEM 2003 GENERAL MOTORS Part # 25876397 (20783865, 25789219). Lock. Latch. Actuator. (Rear). CREW CAB, w/power locks, w/o SLT pkg. Silverado, Sierra; w/o All Terrain; Standard Cab, Crew Cab; Left; w

Exc.Comfort Package. Mechanism to secure door to chassis. Motor to Lock and unLock car door. Assembly - Side. Controller. Door Motor. Dovetail.

Door Latch AssemblyDoor Lock Actuator Motor

Fits Sierra 1500, Sierra 2500 HD, Sierra 3500 HD, Silverado

CREW CAB, w/power locks, w/o SLT pkg. Silverado, Sierra; w/o All Terrain; Standard Cab, Crew Cab; Left; w/Power Doors.
Door Lock Actuator - Repair or Replace
Your 2003 may need a new door lock actuator if your keyless entry doesn't work or your lock button doesn't lock the doors.