K 3500 Truck 4WD V8-5.7L VIN R (1998)
Door Module: Description and Operation
POWER DOOR LOCKS CIRCUIT DESCRIPTION
The power door lock system incorporates door lock switches on both front door and on the RH D-pillar, door lock motors in all passenger doors and
in the RR cargo door, a door lock relay and a door lock control module.
Power for the door lock switches and the door lock control module is supplied from the CIG LTR fuse 13 through CKT 640 (ORN). Power for the
door lock relay is supplied from the PWR ACCY circuit breaker through CKT 540 (ORN). Ground for the door lock relay is supplied from G202
through CKT 150 (BLK) and ground for the door lock control module is supplied from G400 through CKT 150 (BLK).
The door lock motors are reversible and both sides are connected to the normally closed contacts of the door lock relay. Those contacts of the relay
are connected to G202. When any of the door lock switches are placed in the lock position, voltage is supplied through CKT 195 (LT BLU) to the
relay coil. Since the other side of the lock coil is connected to ground, the coil is energized and it pulls the lock contacts closed. Voltage is then
supplied through CKT 295 (GRY) to all the door lock motors and the doors lock. The unlock function operates in much the same manner except that
when any of the switches are placed in the unlock position, voltage is supplied through CKT 194 (WHT) to the unlock coil of the relay and CKT 294
(TAN) supplies voltage to the apposite side of the door lock motor and the doors unlock.
Door Lock Control Module Description
The door lock control module is used on vehicles equipped with cargo doors. The purpose of the module is to lock the cargo doors after a lock cycle
has been commanded from any of the door lock switches with the cargo doors open. When the RH cargo door is open, the module receives a ground
signal from the closed contacts of the rear door jamb switch on CKT 1897 (ORN/BLK) to G400. When a lock command is received, the module
retains this input until it receives an open input from the rear door jamb switch. Then the module sends a lock command through CKT 194 (WHT) to
the door lock relay and the doors lock.
Rear Cargo Doors Description
The power door lock motor will not operate unless the rear cargo doors are fully closed. The power door lock motor is in the right cargo door. The
contactors are on the rear cargo door opening on the body and on the right cargo door.
