Power Door Locks Circuit Description. Chevrolet Astro

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1999 🢒 Astro - 2WD 🢒 Body and Accessories 🢒 Doors 🢒 Power Door Locks Circuit Description

The power door locks are operated by reversible motors. The motors are found in the following locations:

•	In each front door

•	The side door

•	The rear door

The PWR ACCY circuit breaker supplies voltage to the door locks.

If you move either power door lock switch, mounted in the front doors, the LOCK applies voltage to cavity F of the door lock relay. This energizes the lock coil in the relay. Current then flows through CKT 295 (GRY) directly to the following components:

•	Both front door locks

•	The side door lock

•	The rear door lock

•	The motors

CKT 246/294 (TAN) provides the ground for the motors. The normally closed contacts of the UNLOCK then contacts the door lock relay.

If you move one of the door lock switches to UNLOCK the polarity of the system reverses. Current flows through the energized UNLOCK relay contacts. The LOCK relay contacts provide ground.

If the side door is open, the side door jamb sends a ground signal to the door lock control module. If you move the door lock switch to LOCK while the side door is open, the following actions occur:

•	The 2 front doors lock

•	The rear door locks

•	A LOCK signal is sent to the door lock control module at cavity F

When you close the side door, the door jamb switch opens. This breaks a ground signal to the door lock control module. A 5 second timer then starts in the module. After 5 seconds, cavity C of the Door Lock Control Module supplies voltage to the door lock relay. This energizes the door lock relay, which sends voltage to the door lock motors in order to lock the side door.

If the side door opens during this 5 seconds, the 5 seconds timer is reset. The locking pulse takes place at the end of the 5 seconds. Unlocking the door resets the 5 second timer in the door lock control mode.

Use the following components in order to unlock the door lock system:

•	The LH power door lock switch

•	The RH power door lock switch

On vehicles equipped with cargo doors, the cargo door opener mechanically opens the door once the door lock system is unlocked. On vehicle equipped with a liftgate, the liftgate lock/unlock release switch (mechanical key) is added in order to serve the same function as the front power door lock switches. These functions locking and unlocking all doors, including the liftgate. Once the door lock system is unlocked, press the liftgate release switch in order to electrically open the liftgate and pull the handle in order to open the secondary latch.