When the fuel door switch is pressed, 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 fuel door release relay.

The valet switch is a manual control for the coil side of the fuel door 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 fuel door release relay.

When the fuel door release relay closes, battery voltage, that is hot a all times, flows through the 15 A body fuse to the fuel door release relay and then to the fuel door release solenoid.

Ground is then obtained through G302.