GM Service Manual Online
For 1990-2009 cars only

Door Locks with Keyless Entry

The main components in the door locks system with keyless entry are:

    • The body control module (BCM).
    • The door lock switches.
    • The lock/unlock relay.
    • The door lock motors.

Each switch contains a pair of contacts which are normally open. The locks are operated by reversible motors. The switches and the BCM operate the relays by providing voltage to the coil of the appropriate relay. The relays operate the motors by providing voltage and ground. Each motor contains a solid state circuit breaker to prevent overheating and damage to the motor.

When a door lock switch is depressed, voltage is provided through the closed contacts to the lock/unlock relay. The corresponding relay becomes energized and the contacts close providing voltage to the door lock motors. The other relay is normally grounded and provides a path to ground for the motors. With power and ground provided, the motors will operate.

The system operates in a similar manner using the transmitter. The BCM provides the same control of the lock/unlock relay.