Fuel Gauge: Description and Operation

The fuel gauge is an analogue gauge that indicates the level of fuel in the fuel tank with the ignition on. The fuel gauge returns to 0 with ignition off. The gauge reading is proportional to the level of fuel in the tank. It is a damped action gauge to prevent erroneous readings caused by fuel moving in the tank. The damping action is minimized when the ignition is switched on to give an accurate reading within 2.5 seconds.

The signal input for the fuel gauge is from the tank sender unit, it is a variable voltage signal proportional to the level of fuel in the tank. The instrument pack provides the power via fuse 27 to the fuel gauge, then from the gauge on to the fuel tank sender unit. The earth path return circuit of the sender unit is connected to the instrument pack.

A low fuel level signal is provided for the ECM when the sender resistance is greater than 158 ± 8 ohms, this is used to create a fault code indicating low fuel level during misfire diagnosis using TestBook.