Fuel Fill Door Description and Operation European

The fuel door relay switch and coil terminals are supplied with battery voltage at all times via the DR/LCK fuse located in the rear fuse block. The locking and unlocking of the fuel door is a function of the power door lock system. When the vehicles doors are unlocked, the body control module (BCM) receives a GMLAN serial data message that the doors have been locked via a door lock switch or a remote keyless entry (RKE) function. The BCM will respond by applying ground to the fuel door relay control circuit. This energizes the coil causing the switch contacts to close. With the switch contacts closed, battery voltage is supplied to the fuel door release actuator, unlocking the fuel door.

When locking the fuel door, the BCM removes ground from the fuel door relay control circuit causing the relay switch contracts to open. With the relay in an non-energized state, the switch contacts are open to ground at G401. The BCM, upon receipt of a lock serial data signal, will apply ground to the door lock relay. This energizes the door lock relay causing the switch contacts to close. With the switch contacts closed, battery voltage is applied to the fuel door release actuator, rear door locks, rear door deadbolts, and front door deadbolts. The fuel door release actuator is supplied with ground through the open switch contacts of the fuel door relay to ground G401 causing the actuator to lock.