Door Locks: Description and Operation

When either Door Lock Switch is operated, both doors will lock or unlock. Both doors can also be unlocked from the LH and RH Door
Lock Cylinder Switches. When a Door Lock Cylinder Switch is turned to the UNLOCK position, the Body Computer Module (BCM) senses ground at terminal 1D3 which initials the wake-up routine. If the Cylinder Switch is turned to the UNLOCK position again within 10 seconds, the BCM applies momentary battery voltage through terminal 2A4 and the BLK/WHT (194) wire. The Unlock Relay in the Door Lock Relay energizes and both door locks are driven to the UNLOCK position.


When the Trunk Lock Switch is turned to the UNLOCK position, the Body Computer Module (BCM) senses a ground at terminal 2B12 which initials the wake up routine. If the Cylinder Switch is turned to the UNLOCK position again within 10 seconds, the BCM applies momentary battery voltage through terminal 2A4 and the BLK/WHT (194) wire. The Unlock Relay in the Door Lock Relay energizes and both door locks are driven to the UNLOCK position.

The locks are operated by reversible Motors that receive voltage from two Relays in the Door Lock Relay. These Relays operate the Motors by applying battery voltage to one of the terminals and ground to the other terminal.

When any Door Lock Switch is moved to the LOCK position, it completes the circuit to the Lock coil of the Door Lock Relay. The Lock Relay is energized. The contact for the Lock Relay closes, and battery voltage through the YEL/BLK wire is applied to the closed contact.

Voltage is then applied to the GRY wires and the Door Lock Motors, which are grounded by the WHT/BRN wires from the other terminal of the Motors through the contact for the Unlock Relay. The Motor in each door operates the Door Locks. When the Door Lock Switch is released, the Lock Relay contact returns to ground and the Motors turn off.

A similar action occurs when a Door Lock Switch is moved to the UNLOCK position. Now the WHT/BRN wires to the Motors supply battery voltage and the GRY wires are grounded. The polarity of the voltage to the Motors has reversed. The Motors run in the opposite direction to unlock the doors.


The Door Lock Switches are normally closed for a short interval. If the Door Lock Switches are held closed, a solid state circuit breaker in each Motor will open to protect the Motor against damage. The circuit breakers close automatically when voltage is removed from the motor.