F 250 4WD Super Duty V10-6.8L VIN S (2001)
Alternative Fuel Selector Indicator: Description and Operation
NOTE: The descriptions and specifications contained were in effect at the time this information was approved for printing. Ford Motor Company
reserves the right to discontinue models at any time, or change specifications or design without notice and without incurring obligation.
ALT/GAS Switch, ALT/GAS Switch Light
The ALT/GAS switch permits the driver to select which fuel the vehicle will operate on. The ALT/GAS switch is located on the instrument panel.
The ALT/GAS switch only operates when the vehicle is at a stop with the ignition in the OFF position. If the switch is moved while the vehicle is
running, the gaseous fuel system will NOT automatically change fuel mode and no damage to the vehicle will occur. The exception is the vehicles
equipped with the LPG extended-range fuel tank system, which permits the driver to switch between the two LPG fuel tanks while driving.
Prior to starting the vehicle (with the ignition in the OFF position), determine which fuel you intend to use and press the ALT/GAS switch.
When the switch is placed in the ALT position the engine will operate in the gaseous fuel mode, running on CNG or LPG (depending upon
application)
^
A green indicator light will illuminate on the fuel selector switch to indicate that the vehicle is operating in the gaseous fuel mode (CNG or
LPG, depending upon application).
^
The green indicator light operates independently of the fuel selector switch and is controlled by the compuvalve.
When the selector switch is placed in the GAS position, the engine will operate in the unleaded gasoline mode.
The ALT/GAS switch sends a signal to the Compuvalve requesting ALT fuel mode, when placed in the ALT position. If no signal is received by the
Compuvalve, the system defaults to base gasoline mode. The ALT/GAS switch light is incorporated into the ALT/GAS switch. It is controlled by the
Compuvalve and is illuminated when operating in ALT/FUEL mode. If an emission-critical Diagnostic Trouble Code (DTC) is recorded, the
ALT/GAS switch light will change from a steady on to an irregular flashing condition. If a communication fault arises the indicator will flash with a
steady pulse. Once the key is switched to ON, the switch will not change the fuel operating mode. The ALT/GAS switch light has the following status
modes:
-
OFF
-
ON STEADY
-
ON THEN OFF (Quickly or Slowly)
-
FLASHING (REGULAR OR IRREGULAR) (Quickly or Slowly)
The dual tank configuration used on F-Super Duty 350 (if equipped) utilizes a three-position switch for selecting each of the fuel tanks individually
(Gasoline, LPG tank one or LPG tank two) and is designed with two separate ALT lights indicating which LPG tank is in use when illuminated. The
LPG dual tank switch permits the driver to switch between the two fuel tanks while driving.
The selector switch has two gaseous fuel mode positions, LPG1 and LPG2.
One of the two green indicator lights will illuminate on the fuel selector switch to indicate which LPG fuel tank is being used.
The operation of the dual tank ALT/GAS switch ALT lights is different than the single tank ALT/GAS switch. With the dual tank ALT/GAS switch,
when the vehicle is keyed on and the switch is in either ALT fuel position, the corresponding light will illuminate for approximately one second and
then go out. The light will go out regardless of whether there is fuel in the tanks or not. (The single ALT/GAS switch light going out in approximately
one second can indicate no fuel). When the vehicle is cranked the light will come back on and will remain on (while cranking or running) if there is
fuel in the tank. The reason for this operation is that the power for the dual ALT/GAS switch lights comes from the base vehicle fuel pump power
circuit. This power is circuit is energized for one second after key on or while the engine is cranking. After a number of seconds with the key on but
the engine not running, both ALT lights may glow dimly. This is no cause for concern.
