Wrangler 4WD L4-150 2.5L VIN P MFI (1998)
Fuel Gauge: Description and Operation
SYSTEM OPERATION
The fuel gauge gives an indication of the level of fuel in the fuel tank. The instrument cluster circuitry controls the gauge pointer position. The
instrument cluster circuitry calculates the proper gauge pointer position based upon a fuel level message received from the Powertrain Control
Module (PCM) on the Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the fuel gauge sending unit and internal programming to decide what fuel level message is required. The PCM then
sends the proper message to the instrument cluster on the CCD data bus. If the PCM message indicates that the fuel level is below one-eighth of a
full tank, the instrument cluster circuitry turns on the low fuel warning lamp and generates a single chime tone,
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.
