Power Locks: Description and Operation

LOCKING
Setting a power door lock switch to the LOCK position provides an input signal to the Body Control Module (PZM) on CKT 780 (RED/BLK) or CKT 244 (LT BLU). The switch grounds a terminal on the PZM through CKT 51 (BLK/WHT) or 151 (BLK/WHT). The PZM in turn provides an output on CKT 195 (LT BLU) which grounds the lock coil of the power door lock relay. With voltage applied to the lock coil, the power door lock relay energizes, providing power from the CONVENIENCE fuse to the door lock actuators through the closed relay contacts and CKT 295 (GRY). The door lock actuators lock the doors because they are grounded. The RH front and the rear (on four-door models) door lock actuators are grounded at ground G401 through CKT 294 (TAN), the unlock relay contacts and CKT 1250 (BLK). The LH front door lock actuator is grounded at G401 through CKT 694 (TAN), the LH front door unlock relay and CKT 1250 (BLK).

UNLOCKING
The unlocking operation is similar to the locking operation except that the polarity of the voltage applied to the door lock actuators is reversed. The completed circuit causes the actuators to run in the opposite direction, unlocking the doors.

Setting a front door lock switch to the UNLOCK position provides an input signal to the PZM on CKT 781 (ORN/BLK) or CKT 245 (DK BLU). The switch grounds a terminal on the PZM to ground CKT 151 (BLK/WHT) or CKT 51 (BLK/WHT). The PZM in turn provides two output signals which accomplish the unlocking function.

On one circuit, the PZM provides an output on CKT 194 (WHT) which grounds the unlock coil of the power door lock relay. The unlock relay contacts close, providing power from the CONVENIENCE fuse to the RH front and the rear (on four-door models) door lock actuators through the closed relay contacts and CKT 294 (TAN).

Voltage to unlock the LH front door lock actuator is applied through the LH front door unlock relay. During unlocking, the PZM) provides an output on CKT 1391 (LT GRN) which grounds the coil of the LH front door unlock relay. Voltage on CKT 2040 (ORN) energizes the relay coil. The CONVENIENCE fuse supplies power to the front door lock actuator through CKT 2040 (ORN), the closed relay contacts and CKT 694 (TAN).

All of the door lock actuators run because they are grounded through CKT 295 (GRY), the lock relay contacts of the door lock relay and CKT 1250 (BLK).

CENTRAL DOOR UNLOCKING
The LH front door and RH front door lock cylinder switch provides an input to the PZM. This input is CKT 262 (LT GRN) for the LH front door and CKT 265 (LT GRN) for the RH front door. The PZM uses these inputs to control the central door unlock feature. Refer to Computers and Control Systems. Computers and Control Systems

ANTI-LOCKOUT
The PZM disables the power door locks when the PZM receives a key in ignition input signal and a LH front door open input signal. To override the anti-lockout feature, hold the power door lock switch in the lock position for three seconds or more.

DOOR LOCK/UNLOCK FUNCTIONS
The PZM locks and unlocks all doors by the following methods:
^ Door lock/unlock switch activation.
^ Pressing the door lock or unlock switch on the remote function actuator.
^ Auto door lock function enabled.
^ Central door unlocking enabled.

For programming and a description of each locking/unlocking function, refer to Body Control Module Diagnosis. Body Control Module