INSTRUMENTS
88-10 DESCRIPTION AND OPERATION
Fuel tank sender unit
The fuel tank sender unit is combined with the pump. It contains a variable resistor with change in resistance
proportional to the change in level of fuel in the tank.
The resistance of the fuel tank sender unit in relation to tank contents and gauge display is shown in the table below:
The fuel tank sender unit input voltage feed is supplied from the fuel gauge. The earth path return circuit of the sender
unit is connected to the instrument pack.
Tank contents Sender resistance, ohms Gauge display
Empty 245 0
Full 19 1
INSTRUMENTS
88-30 DESCRIPTION AND OPERATION
Water sensor
On vehicles with diesel engines a water sensor is located in the bottom of the fuel filter. The sensor utilises the
different resistance properties between water and diesel fuel to determines the presence of water in the fuel.
The sensor receives a battery voltage supply from the fuel pump relay. The sensor output is supplied to the instrument
pack. The water sensor provides the earth path to illuminate the warning lamp.
l< 1.8 volts = warning lamp on.
l> 7.7 volts = warning lamp off.
