Fuel level indicator

Fuel gauge (type UK-193) works in conjunction with the BM-150 sensor installed in the fuel tank. The sensor is made in the form of a nichrome wire rheostat. The moving contact of the rheostat is moved by the float lever. At the end of the lever there is an additional contact that closes the signaling lamp circuit when 4–6.5 liters of fuel remain in the tank.

The serviceability of the fuel gauge sensor can be checked with an ohmmeter.

Data for checking the fuel gauge sensor

The amount of fuel in the tank	Sensor resistance, Ohm
empty tank	315–345
half tank	100–135
Full tank	7 or less

The arrow of the device constantly shows a full tank

With the ignition on, disconnect the pink wire from the sensor. If the arrow returns to the beginning of the scale, the sensor is faulty. Otherwise, either the device is faulty, or the wire is shorted to «mass». To check, remove the instrument cluster (see Removing the instrument cluster), disconnect the gray wire with a red stripe from the pointer and turn on the ignition. If the arrow returned to the beginning of the scale, the fuel gauge is OK, and the wire is damaged.

The arrow of the device constantly shows an empty tank

With the ignition on, disconnect the wire from the output «T» sensor and connect it to «weight». If the arrow deviates, the sensor is faulty. If the arrow does not deviate, remove the instrument cluster (see Removing the instrument cluster) and disconnect the gray wire with a red stripe from the output of the fuel gauge and connect it to «weight». If the arrow deviated, the device is working, and the wire between the sensor and the fuel gauge is damaged.