If the electrical part is protected by a fuse. The first step is to check the fuse. The location of the required fuse is determined by the diagram printed on the cover of the fuse box - see also chapter "Replacing fuses".
The defective fuse is replaced and after switching on the consumer of electricity, it is necessary to check whether the fuse does not blow out immediately again. If the fuse is blown again, the fault should be found and repaired, usually a short circuit. This means that in some place, perhaps also inside the device, the mass and the positive conductor are connected to each other.
The second step of the check is that if the incandescent lamp does not light or the electric motor does not work with a good fuse, it is necessary to check the presence of supply voltage.
Incandescent lamp test
Remove the lamp and inspect. If the incandescent pump is burned out or weakly seated in the base, it should be replaced.
To eliminate doubts about the health of the lamp, proceed as follows, connect one conductor to the positive (+), and the other - to the negative (-) battery poles, and the free ends of the conductors are connected to the lamp. It does not matter how the conductors are connected to the lamp. One conductor - to the current-carrying connector, and the other - to the lamp body. If the lamp does not light up, it should be replaced.
Note. Make sure that the contacts of the lamp and the lamp socket are not rusted. If necessary, clean rusted or bent contacts and bring them to perfect condition.
If the lamp is working, insert the lamp and turn it on. If it does not light up, use a test lamp to check the presence of supply voltage. To do this, connect the test lamp to ground. This means that one wire of the test lamp must be connected to a reliable engine ground (clean metal surface) or directly with the negative pole of the battery. Other indicator lamp electrode (+) must be connected either to a current-carrying plug, or plugged into a current-carrying wire. If now the control lamp lights up, and the incandescent lamp still does not burn, then there is a break in the ground wire. To check this, you need to install a jumper from ground to the lamp socket. In this case, the lamp should light up.
Note: there are lamps to which voltage is supplied by only one conductor, for example, lamps for parking lights, interior lighting of a car. These lamps are connected to the vehicle ground directly by their housing. If the current-carrying conductor of the lamp has no voltage, that is, the control lamp does not light up, it is very likely that the switch is faulty. Check switch.
Checking electric motors
More and more small-sized electric motors are used in the car to increase comfort. They are used in mechanisms such as power windows, sliding roof panel, electrical central locking or electrical antenna control.
Each electric motor is turned on with a switch if necessary, in most cases by hand. At the electrical antenna, the switch is controlled automatically by the radio.
Check the fuse of the relevant electric motor, replace the fuse if necessary.
Note: The cause of the motor overload must be corrected before the power window and central locking system can be reactivated. Overloading can be caused by icing on windows and door locks, or dirty window guide rails.
If the fuse blows again immediately, there is a short circuit.
To unambiguously find out if the pi electric motor is working, it is necessary to connect it with two auxiliary wires with a diameter of approximately 2 mm directly to the vehicle's battery. The positive pole of the battery must be connected to the positive motor connector and the negative pole to the negative connector. The location of the positive and negative motor connectors, in case of doubt, is determined in accordance with the electrical diagram. If necessary, the motor is removed. All electric motors of the car are powered by on-board voltage from 12 to 14 volts. If the motor is now running normally, the cause of the problem was a lack of supply voltage.
Note: If the motor rotates slowly or intermittently, worn carbon brushes may be the cause and should be replaced.
If the electric motor is running, use the wiring diagram to determine which conductor supplies voltage to it when the switch is pressed and before the ignition is turned on.
Check the voltage supply wire with a test lamp. Since a large current flows through the electric motor, you can use a conventional incandescent lamp as a test lamp. It is equipped with sharp electrodes that can be used to pierce the connecting wire. This allows a simple way to determine the presence of the supply voltage. Reversible electric motors, such as power windows, have two positive connections.
Attention: Checking the wiper motor is described later in the corresponding chapter.
If voltage is not supplied to the electric motor, the supply circuit is faulty. Find the fault in the wiring according to the wiring diagram and fix it. Due to the need for high currents, electric motors usually have an additional switching relay. Relay testing is described in the relevant chapter.
If no fault was found, check the switch.
If there is a defect in the wire, then it is advisable to lay a new wire, since it is rather difficult to localize the defect in the wire.
Circuit breaker test
Most electrical consumers are switched on and off manually via a switch. In addition, there are switches that operate automatically. Such switches include, for example, hydraulic switches and brake fluid level switches.
The main task of the switch is to close and open the electrical circuit. There are switches that open the ground wire and switches that open the positive voltage wires.
Checking lamp and motor switches
Remove the relevant switch.
Simple switches have only 2 wire connectors. In this case, the positive voltage (+) is always applied to one connector, and after the switch is turned on, positive voltage is also applied to the other connector. There are also switches with an increased number of connectors. According to the electrical diagram, you should find out which connectors in such switches should be energized, if necessary, first turn on the ignition.
Use a test lamp to check whether voltage is supplied to the supply connector of the switch. If the test lamp lights up, turn on the switch and check for voltage at its output connector. If there is tension, it can be stated. that the switch is OK.
If there is no voltage on the supply connector of the switch, then there is a break in the current supply circuit. Check the current supply circuit according to the wiring diagram and lay a new wire if necessary
Checking the sensors-switches
Such switches include, for example, hydraulic switches and sensors-switches for the level of coolant and brake fluid.
Connect a breaker tester (test lamp or ohmmeter) to the inlet and outlet wires of the switch, for which one wire should be removed from the switch.
Attention: Switches that are screwed into the engine block, as a rule, do not have a ground wire, since this function is performed by the switch housing.
When the circuit breaker is on, the tester should show the conductivity of the circuit breaker. This is best determined with an ohmmeter: when the switch is on, it should show 0 ohms, and when it is off, it should show ∞ (infinity) Ohm.
The operability of the sensor-switch of the coolant or brake fluid level indicator can be checked most quickly if, with the ignition on, remove the supply wire from the sensor and connect it to a reliable ground, for example, an engine block. If the indicator lamp lights up, then the switch is faulty.
Distinctive feature of the hydraulic switch: when the engine is not running, the contact of the switch is closed (signaling device is on). Only at a certain pressure does the contact open and the signaling device goes out.
Relay test
Relays are built into many electrical circuits. The switching relay works as a switch. Example: when the high beam is turned on by the manual switch, the relay is commanded to energize the high beam headlights. Of course, it would be possible to supply current to the high beam headlights from the battery directly through the light switch. However, for all consumers requiring high current (high beam headlights, windshield wipers. fog lights), include an intermediate relay so as not to overload the switch and guarantee the circuit from a short circuit. In addition to the switching relays, there are also functional relays, for example, for the glass cleaning and washer system or the warning sound alarm relay in the outdoor lighting switching circuit.
Checking the switching relay
When the corresponding consumer is switched on, the control function of the relay is activated. In this case, the electromagnet coil inside the relay attracts the contact and thereby closes the electrical circuit of the operating current. The operating current through the relay flows further to the consumer.
The easiest way to check the performance of the relay is to replace it with a good one. This is how they do it at the station. Since the motorist only in very rare cases has a new relay at his disposal, the following sequence of operations is recommended with the so-called switching relays, which are used to switch on the fog and main headlights. The terminal designations given below, especially for serially installed relays, may differ.
Pull the relay out of the holder.
Switch on the ignition and operate the appropriate switch.
First, use a voltage tester to determine if voltage is applied to the positive terminal (+) relay boards. To do this, connect one electrode of the tester to ground (-), and carefully insert the other electrode with a sharp end into the terminal. If the light diode of the device lights up, then the voltage is applied. If the device shows no voltage, guided by the electrical circuit, find an open circuit in the area from the positive pole (+) battery to the positive terminal.
Make a jumper from a piece of insulated wire, cleaning the ends of the jumper to a shine.
Connect the terminal with this jumper (+) relay boards (This terminal is always supplied with voltage from the positive pole of the battery) with relay output terminal. This operation practically does the same thing that a good relay does. Where the terminals are located on the relay board can be determined by the color of the wires and by the electrical diagram.
When, for example, the main beam lights up with the jumper installed, it can be concluded that the relay is faulty.
If the main beam does not light up, it is necessary to find out if the headlight ground connection is correct. Then, guided by the electrical circuit, find and repair an open in the wiring from the relay terminal to the main headlights.
If required, install a new relay.
Checking the wiper motor
The wiper motor is located under the windshield in a drainage casing. The appropriate cover must be removed for inspection. The following is a description of the work in relation to the windshield wiper. For the rear window wiper, proceed in a similar way.
Terminal designations
The motor terminals are unified.
- Terminal 31 is used for earth connection (in all automotive electrical engineering).
- Terminal 53 is energized for the first wiper speed.
- Terminal 53a receives positive voltage (+) to move the wiper to its original position, after the driver turns off the wiper, the electric motor receives voltage through the brush until the wiper blades are in their lowest position.
- Terminal 53b is energized for second wiper speed (parallel winding).
- It is not always available, via terminal 53e, that the motor is braked during reverse operation after switching off, so that the wiper does not exceed its stop position.
- Not always available, terminal 53c (from the relay) connects to the electric window washer pump, terminal 53i is available for permanent magnet wiper motors with a third wiper blade (for high speed).
Checking the wiper motor
First of all, it is necessary to find out whether the electric motor is faulty or there is no supply voltage. To do this, proceed as follows.
Disconnect the multi-pin connector of the motor.
Using two auxiliary wires, connect the positive to the motor (+) and negative (-) battery voltage.
- connect the wire from the positive pole to terminal 53 or 53b;
- Connect the wire from the negative pole to terminal 31.
Now the wiper motor should operate at the first or second speed, depending on the terminals involved. If this is not the case, then the electric motor or its corresponding winding is faulty. Remove wiper motor see p. 186.
Flashing light test
Switching on and off the flashing light signaling device and the emergency light signaling system is carried out by means of a relay, the so-called turn signal interrupter. The hazard warning light system is connected to a relay without a fuse. The flashing turn signal light circuit is protected by a fuse located in the fuse box.
If the rhythm of the flashing of the direction indicator lights on one side is faster than on the other, then where the flashing is more frequent, there is a defect in the incandescent lamp or a wire break.
In most other cases, the cause of the malfunction is a defective turn signal relay. Terminal arrangement (pins) turn signal breaker has the designations:
- terminal 31 is used for earth connection ("-" in all automotive electrical engineering);
- terminal 49 is a relay input (a constant positive voltage), and terminal 49a is the relay output.
If a new relay is not available, carefully insert a thin wire between terminals 49 and 49a of the relay plug.
Attention: In doing so, the indicated contacts must not be damaged. Before sticking, bend the ends of the wire so that there are no sharp edges. Reinsert the defective turn signal relay. Turnip pins are so long that, despite the jumper, they allow you to do this.
Turn on the ignition. If you now use the turn signal switch lever, then the direction lights on the corresponding side will be continuously lit. The rhythm of turning the lights on and off can be created using the turn signal switch lever.
If, despite the jumper of the relay contacts, the direction indicator lights do not light up, then the cause of the malfunction lies either in the direction indicator switch or in the electrical wiring.
Checking the brake signal
If the brake light does not come on, first check the condition of the fuse in the fuse box.
If the fuse is OK, then you need to check the brake light bulbs, if necessary, replace the bulbs.
If the brake light bulbs are OK, check the brake light switch. The switch is located on the pedal bracket above the brake pedal. When the brake pedal is depressed, the contact pin extends from the switch. The switch contact closes and the brake light comes on.
Check the brake light switch. To do this, disconnect the 2 plug connectors of the switch.
Turn on the ignition.
With a short auxiliary wire, make a jumper between the contacts of both plugs. If the brake light comes on, then the brake light switch is defective.
Replace brake light switch.
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