GM Service Manual Online
For 1990-2009 cars only

When the trunk release switch is pressed it a 5 V reference signal from the drivers door switch is grounded that is obtained through the driver's door module (DDM).

The drivers door switch sends this signal to the DDM via a simple bus interface.

The DDM then sends a Class 2 message to the rear integration module (RIM). The RIM will then check to see if the vehicle is in PARK. When these conditions are met the RIM will ground the coil side control circuit of the trunk release relay.

The valet switch is a manual control for the coil side of the trunk release relay. Battery voltage that is hot at all times flows through the 10 A ALDL fuse through the valet switch and then to the coil side of the trunk release relay.

When the trunk release relay closes, battery voltage, that is hot a all times, flows through the 15 A body fuse to the trunk release relay and then to the rear compartment lid release actuator.

Ground is then obtained through G402.