RAM 3500 Truck 2WD V10-8.0L VIN W (1997)
Low Fuel Lamp/Indicator: Description and Operation
SYSTEM OPERATION
The low fuel warning lamp will light when the fuel level in the fuel tank has fallen below about one- eighth of a full tank, as registered on the fuel
gauge. One side of the low fuel warning bulb is grounded at all times. A low fuel warning circuit attached to the rear of the gauge cluster provides
ignition-switched battery voltage to the lamp when the fuel level is low.
The low fuel warning circuit monitors the signal from the fuel level sending unit. When the circuit senses about 65 ohms or more from the fuel
level sending unit for eight to thirty continuous seconds, the indicator lamp will light. The indicator lamp will remain on until the circuit senses
about 65 ohms or less from the fuel sender for eight to thirty continuous seconds.
The fuel gauge sending unit is mounted to the electric fuel pump module inside the fuel tank. The sending unit has a float attached to the end of a
swing- arm. The float moves up or down within the fuel tank as the fuel level changes. As the float moves, an electrical contact on the pivot end of
the swing-arm wipes across a resistor coil, which changes the resistance of the sending unit.
CIRCUIT OPERATION
Circuit G4 connects the fuel level sensor to the low fuel relay in the instrument cluster. When the fuel level in the fuel tank reaches a calibrated
level, the low fuel warning lamp relay illuminates the lamp.
