F 150 Super Crew 4WD V8-5.4L Prop SOHC VIN Z (2003)
Fuel Tank Switching Valve Relay: Description and Operation
ALT Fuse/Relay Module
The ALT fuse/relay module contains two replaceable fuses. Refer to the Vehicle/Diagrams for fuse location. Fuse 1 (3A) protects the Battery feed
(BATT) to the compuvalve and Fuse 2 (10A) protects the BATT to the ALT fuel power relay, in turn protecting the VPWR circuits of the
compuvalve. The ALT fuse/relay module also contains two dual mini ISO relays: the ALT fuel power relay and the fuel pump cutoff relay. The ALT
fuel power relay provides power to the compuvalve when the key is in the ON position. The fuel pump cutoff relay interrupts the power to the gasoline
fuel pump from the base gasoline fuel pump relay when the ALT/GAS switch is placed in the ALT position.