Checking the devices (VAZ-2121)

Contents: Coolant temperature gauge ↓ Fuel level indicator ↓ Oil pressure gauge ↓ Tachometer ↓ Speedometer ↓

Coolant temperature gauge

Device type - UK-193; The device operates together with the TM-106 sensor. With a sensor resistance of 640-1320 Ohm, the arrow should be at the beginning of the scale, with a resistance of 77-89 Ohm - at the beginning of the red section, and with a sensor resistance of 40-50 Ohm, it should deviate to the end of the red section of the scale.

Fuel level indicator

The device type is UB-193. It is used in tandem with the BM-168 sensor, which is installed in the fuel tank. This sensor also turns on the fuel reserve indicator light if there are 5.3-6.5 liters of gasoline left in the tank:

If the sensor resistance is 285-335 Ohm, the arrow should be at the beginning of the scale, if the resistance is 100-135 Ohm, it should be in the middle of the scale, and if the resistance is 7-25 Ohm, it should be at the end of the scale.

Oil pressure gauge

Indicator type UK-194. The device has a control lamp for insufficient oil pressure, which is switched on by a sensor of the MM-120 type.

The indicator is used together with the sensor type MM393A, changing the resistance of the electric circuit depending on the oil pressure in the engine lubrication system. With a sensor resistance of 285-335 Ohm, the indicator arrow should be at the beginning of the scale, with a resistance of 100-135 Ohm - in the middle of the scale, and with a resistance of 0-25 Ohm - at the end of the scale.

Tachometer

The car is equipped with an electronic tachometer TX-193. The principle of operation of the tachometer is based on measuring the frequency of voltage pulses in the primary circuit of the engine ignition system.

The tachometer is tested on a stand simulating the ignition system of a car. Having connected the tachometer to the stand circuit in the same way as on the car, set the voltage in the primary circuit to 14 V and the gap in the stand spark gap to 7 mm. Rotate the distributor shaft at such a speed that the tachometer needle reaches one of the scale divisions. At this point, check that the distributor shaft rotation frequency is within the limits specified in Table 7-6.

Table 7-6. Tachometer Check Data

Countdown, min⁻¹	Distributor shaft rotation speed, min⁻¹
1000	440-550
2000	875-1050
3000	1350-1525
4000	1850-2025
5000	2350-2500
6000	2900-3000
7000	3350-3500
8000	3800-4200

Speedometer

The speedometer type SP-193 consists of an arrow indicator of the vehicle speed in km/h, a final counter of the distance traveled by the vehicle in km, and a daily odometer of the vehicle.

The daily counter readings can be reset using the handle located on the instrument panel. To do this, turn the handle counterclockwise.

To avoid damaging the meter, do not reset it while the vehicle is moving.

Check the speedometer by comparing its readings with the standard one. The data for checking are given in Table 7-7.