GM Service Manual Online
For 1990-2009 cars only

The power door lock system locks or unlocks all doors with the actuation of a single door lock switch. Power is available at all times from the DOOR LOCK fuse through CKT 1240 to the following components:

    • The left front door lock switch
    • The right front door lock switch

This voltage is also supplied to the following relays:

    • The door lock relay
    • The door unlock relay

Both relays are grounded through CKT 150 at G201.

Each door lock switch has two contacts. When the upper portion of the door lock switch is depressed in order to unlock the doors, one contact closes in order to apply voltage to CKT 194. This voltage is applied to the coil side of the door unlock relay. Since the coil in the relay is grounded at all times through CKT 150 and G201, the coil is energized. The relay switch contacts then close in order to apply voltage to CKT 294. CKT 294 applies voltage to all the door lock motors, which are grounded through the following components:

    • CKT 295
    • The normally grounded contacts of the door lock relay

When the lower portion of the door lock switch is depressed in order to lock the doors, the other switch contact closes in order to apply voltage to CKT 195. This voltage is applied to the coil side of the door lock relay. Since the coil in the relay is grounded at all times through CKT 150 and G201, the coil is energized. The relay switch contacts then close in order to apply voltage to CKT 295. CKT 295 applies voltage to all the door lock motors which are grounded through the following components:

    • CKT 294
    • The normally grounded contacts of the door unlock relay

With Keyless Entry

When the vehicle is equipped with keyless entry, the following doors operate as described above:

    • The right front door
    • Both rear doors

The left front door lock motor does not operate in the same manner. When either door lock switch is moved to the LOCK position, the operation is similar to the above operation, with the following exceptions:

    • The left front door lock motor receives ground through CKT 694.
    • The left front door lock motor receives ground through the remote control door lock receiver.

If either door lock switch is moved to the UNLOCK position, the following components receive voltage:

    • CKT 194
    • The remote control door lock receiver

When the remote control door lock receiver receives the unlock signal, the receiver then applies voltage to the left front door lock motor through CKT 694. The motor is then grounded through CKT 295 as described above. Refer to Keyless Entry System Description in Keyless Entry.