Power Locks: Description and Operation

CIRCUIT OPERATION

Locking
When a Door Lock Switch is in the lock position, voltage from Fuse C3 is applied to the Door Lock Relay's lock coil through the closed contacts of the Door Lock Switch and CKT 195. With voltage applied to the Door Lock Relay's lock coil, the relay energizes, allowing voltage from Circuit Breaker 3 to be applied to the Door Lock Motors through the closed relay contacts and CKT 295. The door lock motors lock the doors since they are grounded at ground G401 through CKT 294 and the unlock relay contacts. If the car is equipped with the Keyless Entry System, the LH Front Door Lock Motor is also grounded at G401 but the ground path is through the CKT 694 and the Keyless Entry Module.

Unlocking
The unlocking operation is similar to the locking procedure except the Door Lock Relay reverses the Door Lock Motors polarity. This makes the motors run in the opposite direction, unlocking the doors. When a Door Lock Switch is in the unlock position, voltage is applied to the Door Lock Relay's unlock coil energizing the relay.

The relay's unlock contacts now close to apply voltage to the Door Lock Motors through CKT 294. The Door Lock Motors are grounded through CKT 295 and the lock relay contacts at ground G401.

Keyless Entry
When a vehicle is equipped with a Keyless Entry System, the LH front door is wired differently. This allows the driver to unlock only the LH front door without unlocking any other doors using the Keyless Entry transmitter,

The wiring difference does not change the locking operation except that the LH Front Door Lock Motor is grounded through the Keyless Entry Module. All of the other door locks motors in the car are grounded through the Door Lock Relay's unlock contacts and CKT 294.

The wiring difference does affect the unlock operation of the LH Front Door as compared to the other doors. For the LH front door to be unlocked using a door lock switch, voltage must be applied to the Keyless Entry Module's terminal C2. This application of voltage occurs through CKT 194 when any door lock switch closes to the unlock position. The module responds by applying voltage to the LH Front Door Lock Motor through CKT 694. The Motor is grounded through CKT 295 and the Door Lock Relay. The module also applies voltage to the LH Front Door Lock Motor through CKT 694 when the Remote Keyless Entry transmitter's unlock button is pushed.