Before starting to troubleshoot any electrical circuit, carefully study the corresponding diagram to clearly understand its functional purpose.
The fault search range usually narrows by gradually identifying and eliminating normally functioning elements of the same circuit.
When several elements or circuits fail simultaneously, the most likely cause is a blown fuse or a poor ground connection (different circuits may be connected to a single fuse or ground terminal).
Electrical failures are often caused by simple reasons such as corrosion of connector contacts, blown fuse, melted fusible link, or damaged relay.
Visually inspect all fuses, wiring, and circuit connectors before proceeding to a more detailed check of its components.
If using diagnostic instruments for fault finding, carefully plan (according to the supplied electrical diagrams) which points of the circuit and in what sequence to connect the instrument to most effectively identify the fault.
Checking indicators and sensors of vehicles manufactured before 2003
Oil pressure indicator
To check the oil pressure indicator 23.3829, remove the instrument cluster - "How to remove and install the instrument cluster"
Assemble the circuit
With a resistance of 300 Ω, the needle should be at the zero mark of the scale; with 180 Ω, at the beginning of the green zone.
With 68 Ω, the needle should move to the beginning of the red zone.
An emergency oil pressure sensor is also installed in the cylinder head; it must open its contacts at a pressure of 40–80 kPa (0.4–0.8 kgf/cm²).
Coolant temperature indicator
The coolant temperature indicator 37.3807 works with the TM-106-10 temperature sensor screwed into the cylinder head.
The sensor contains a thermistor (a resistor that changes its resistance depending on temperature).
You can check the sensor with an ohmmeter. A working sensor should have a resistance of 1400-1900 Ω at 20–25 °C (needle at the beginning of the scale) and 100-110 Ω at 80 °C (needle at the boundary of the green and white zones).
The sensor is non-repairable and cannot be disassembled.
Removing the temperature sensor from ZMZ-402 type engines
Removing the temperature sensor from ZMZ-405, ZMZ-406 type engines
Remove the sensor.
To check the temperature indicator, remove the instrument cluster (see article - "How to remove and install the instrument cluster")
Assemble the circuit shown in the figure.
With a resistance of 68 Ω, the needle should be in the middle of the red zone; with 180 Ω, at the beginning of the green zone; with 910 Ω, at the beginning of the white zone.
A TM 111-02 coolant overheat warning sensor is also installed in the cylinder head.
The sensor should trigger at a fluid temperature of 104 – 109 °C.
Fuel level indicator
The fuel level indicator 32.3806 works with the sensor 5412.3827 installed in the fuel tank.
The sensor is a rheostat with a nichrome wire resistor.
The movable contact of the rheostat is moved by a lever with a float.
There is an additional contact at the end of the lever that closes the warning lamp circuit when reserve fuel remains in the tank.
You can check the fuel level sensor with an ohmmeter.
Replace the faulty sensor.
To check the fuel level indicator, remove the instrument cluster.
Perform tests by successively changing the resistances.
With 330 Ω, the indicator should show an empty tank; with 118 Ω, half a tank; with 11 Ω, a full tank.
Data for checking the fuel level sensor
- Empty tank - 315-345 Ω;
- Half tank - 108-128 Ω;
- Full tank - 6-16 Ω
Voltmeter
You can check the voltmeter by comparing its readings with those of a standard multimeter.
Before testing, we recommend keeping the voltmeter under 12 V voltage for about 5 minutes.
Replace faulty instruments: use a flathead screwdriver to unscrew the eight self-tapping screws.
Remove the frame with the glass.
Use a 5.5 mm socket to unscrew the mounting nuts of the faulty instrument.
Remove the instrument.
Install a new instrument into the cluster in reverse order.