When the ignition switch is in the run position and the 4WD control lever is in the 4WD position, the transfer case switch closes, supplying a ground on the front axle actuator/switch control circuit. With the ground applied, the lodgic of the actuator/switch actuates a DC motor to engage the front axle and supply voltage to the four wheel drive (4WD) front wheel lock telltail feed circuit. This voltage notifies the PCM/VCM and the Anti-Lock Brake System that the vehicle is in the 4WD mode. When the 4WD control lever is in the 4WD Low range position, the transfer case switch closes and supplies a ground on the four wheel dive (4WD) switch signal low circuit. This informs the VCM/PCM that the vehicle transfer case is in Low range. When the vehicle is in Low range, the VCM/PCM changes the shift pattern of the automatic transmission. Ignition voltage is supplied on terminal C of the front axle actuator/switch through the 4WD fuse located in the Fuse Block.