RAM 2500 Truck 2WD L6-359 5.9L DSL Turbo VIN D FI (1997)
Fuel Gauge: Description and Operation
SYSTEM OPERATION
The fuel gauge gives an indication of the level of fuel in the fuel tank. The fuel gauge sending unit is mounted to the electric fuel pump module
located 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
internal electrical resistance of the sending unit.
High sending unit resistance causes low fuel gauge readings. Low sending unit resistance causes high fuel gauge readings. The sending unit
resistance values are shown in a chart in Specifications.
CIRCUIT OPERATION
Circuit G4 connects the fuel level sensor to the fuel gauge in the instrument cluster. Circuit F14 from fuse 12 in fuse block supplies voltage to the
fuel gauge. The fuel level sensor draws voltage from circuit F14 through the fuel gauge on circuit G4. The fuel level sensor is located in the fuel
tank.
As current flows through the coils in the fuel gauge, it creates a magnetic field. One of the coils in the gauge receives fixed current. The other coil
is connected to the level sensor. The magnetic field controls the position of the fuel gauge pointer.
The fuel level sensor contains a variable resistor. As the position of the float arm on the fuel level sensor changes, the resistor changes the current
flow through the second coil in the fuel gauge. A change in current flow alters the magnetic field in the fuel gauge, which changes the pointer
position.
Circuit Z11 provides the ground path for the fuel level sensor.
