The first step is always to check the fuse as it protects the electrical component. The actual location of the fuses can be seen on the print located on the cover of the fuse box.
If necessary, replace the defective fuse and after connecting the electrical consumer, check if it has blown again. In this case, first of all, it is necessary to detect a malfunction and eliminate it, here, as a rule, we are talking about a short circuit.
The second control step: If, with a good fuse, the incandescent lamp does not light, or, accordingly, the electric motor does not work, then the power supply system should be checked.
Incandescent lamp test
Remove and inspect the lamp. If the filament is burned out or the glass bulb sits loosely in the base, then the lamp should be replaced.
To determine if the incandescent lamp is working, proceed as follows:
Connect directly to the positive battery terminals (+) and grounding (on the car body) the wire (–) and connect them to the lamp. It does not matter which wires are connected to the lamp. Connect one wire to the conductor, the other to the body of the incandescent lamp. If the lamp still does not light up, replace it.
You must be sure that the contacts on the lamp and lampholder are not corroded. If necessary, smooth out correlated or bent leads with sandpaper and make a normal contact.
If the lamp is good, insert it and turn it on. If the lamp does not light up, use a test lamp to check the power supply. To do this, connect the control bulb to the vehicle ground. i.e., one test light wire should be connected to a good case point on the engine (polished metal) or directly to the negative battery terminal. Another test light probe (+) either hold it on a live plug or connect it to a live wire. If now the control lamp lights up, but the lamp still does not burn, then the line connecting the car body to the incandescent lamp is broken. To check this, attach an auxiliary wire connected to the car body to the lamp socket. Now the incandescent lamp should light up.
Note: There are lamps that are equipped with only one energized supply line, eg parking light, vehicle interior lighting. These lamps are directly connected to the mass of the vehicle through their housing.
If there is no voltage in the current-carrying wire to the lamp and the control lamp does not light up, then it is very likely that the switch is faulty. Check the switch for current flow.
Checking electric motors
In the car, ever-increasing comfort is provided by low-power electric motors. These include, for example, a power window, a moving roof panel, a centrally operated door lock system or an electrical antenna. If necessary, each electric motor is turned on with a single switch, usually manually. In the case of an electrical antenna, the switch is automatically controlled via a radio receiver.
Check the resistance of the respective motor, replace it if necessary.
Attention! Eliminate the cause of overloading the power window and central locking system before reactivating. This can be, for example, frozen glass and locks or dirty grooves of the lowered glass.
If the fuse immediately blows again, this indicates a short circuit.
To unambiguously find out if there is a malfunction in the engine, run two auxiliary wires with a diameter of about 2 mm directly from the car battery to the electric motor. Connect the positive wire to the positive pole and the wire connected to the body to the ground pole. In case of doubt, the distribution of poles is determined from the circuit diagram of the electrical installation. If necessary, to do this, you need to disassemble the electric motor. All electric motors in the car are powered by on-board voltage (12 to 14 Volts). If the motor is now running normally, the electrical system was faulty.
Attention! A motor that runs too slowly or runs rough may indicate that the electrographite sliding contacts are worn out. In this case, replace these contacts.
If the engine is running, then according to the electrical diagram, determine which supply wire supplies voltage to the electric motor when the switch is activated with the ignition previously turned on.
Using a test light, check the live wire in the motor. Since a large current flows in electric motors, it is possible to replace a conventional control light with an incandescent lamp. These lamps are equipped with pointed test needles that can be used to pierce the connecting wire. In this simple way, you can check the voltage. Motors that rotate left/right alternately, such as power window motors, have two positive terminals.
Attention! Check wiper motor.
If voltage is not supplied to the electric motor, then the power supply system is faulty; find a defect in the supply line according to the circuit diagram of electrical equipment and eliminate it. As a rule, due to the high current consumption, electric motors have an additional switching relay.
If no fault is found, check the switch.
If the wire is damaged, it is often more rational to lay a new wire, since it is difficult to determine the place of the break under the insulation.
Checking switches for current flow
Most electrical consumers are turned on and off with a manually operated switch. In addition, there are switches with automatic drive. Such switches include, for example, a hydraulically actuated switch (brake pressure drop sensor) and a brake fluid level sensor.
In principle, a switch has the task of closing or breaking an electrical circuit. There are breakers that break the ground line and breakers that break the positive pole line.
Checking lamp and motor switches
Remove the appropriate switch.
Simple switches have only two leads for connecting a wire. In this case, voltage should be applied to one output (+), and after switching on / off - to another output. Switches with multiple terminals are available. With these switches, the circuit diagram explains which terminal the voltage is to be applied to. If necessary, turn on the ignition beforehand.
Use a test light to check if voltage is being supplied to the switch. If the control lamp lights up, turn on the switch and check if voltage is also supplied to the output terminal. If so, then the switch is found to be functioning.
If there is no voltage at the output terminal, then there is a break in the power supply wire. Based on the circuit diagram of the electrical system, check the voltage supply and, if necessary, lay a new wire.
Checking the switches-sensors
Switch-sensors, for example, are a hydraulic switch, brake and coolant level sensors.
Plug in the probe (test lamp or ohmmeter) to the input and output wires of the switch, to do this, remove the wire from the switch.
Attention! Switches that are screwed into the engine block usually do not have a wire connecting them to the housing, since the switch housing on top of the engine block serves as a grounding pole.
When the switch is on, the probe should indicate "current flow". The best probe is an ohmmeter: when the switch is on, it shows zero ohms, and when it is off, it shows infinity.
The fastest way to roughly test the coolant and brake fluid level warning switches is by pulling the lead wire off the switch with the ignition on and pressing it to a well-grounded location, such as the engine block. If the warning light on the instrument panel comes on, the fault is in the switch. A special case is a hydraulically actuated switch (brake voltage drop sensor): when the engine is stopped, the contact is closed (warning light is on), the switch opens only at a certain oil pressure.
Relay test
Relays are installed in many electrical circuits. The switching relay works like a switch. Example
: If the high beam is turned on with the manual switch, the relay is commanded to switch the current to high beam. Of course, it would be possible to supply current directly from the battery, by means of a light switch. But for all elements with high current consumption (high beam, wiper, fog lamp) a relay is connected to the circuit so as not to overload the switch, providing shorter current paths. Near these combination relays are also functional relays, for example, for windscreen cleaning and washer systems or a warning buzzer for switched on outdoor lights.
Checking the switching relay
When the lighting element is turned on, the relay starts, i.e. using the switching current, the electromagnetic coil draws in the relay contact and thus closes the electrical circuit "operating current". The operating current through the relay goes further to the consumer. The easiest way to check the performance of the relay is to replace it with a good one. This is what they do even in the auto repair shop. Since the vehicle owner rarely has a new relay immediately available, in such cases it is recommended to carry out the following operation in the case of so-called switching relays, which are used, among other things, to turn on the fog and main lights. The marking of the terminals shown here, especially for serially installed relays, can also be presented in a different way.
Remove the relay from the holder.
Turn on the ignition and the corresponding switch.
First check with a voltage indicator whether voltage is applied to terminal 30 (+) into the relay holder. To do this, connect a voltage indicator to the case (–), and insert the other contact carefully into terminal 30. If the light emitting diode flashes, there is voltage. If the voltage indicator does not show voltage, then look for a break in the wire coming from the positive pole of the battery using the circuit diagram (+) to terminal 30.
Make a conductive jumper from a piece of insulated wire, stripping it to a shine.
Use this jumper in the relay carrier to connect terminal 30 (+ battery is always energized) with NO contact output on terminal 87. This work step is practically the same as when installing a good relay.
If with a jumper, for example, the main beam lights up, then we can assume that the relay is faulty
If the high beam does not light up, find out if the connection to the housing at the headlights is in order. In this case, locate and repair the open in the line from terminal 87 to the main headlight using the wiring diagram. Install a new relay if required.
Attention! If a defect in an electrical circuit that is equipped with one relay appears only periodically, then in this case, as a rule, the malfunction lies in the relay: the contact in the relay disappears or the contact sticks too much, while the rest of the time the relay functions normally. If a defect occurs, lightly tap on the relay housing. If the relay switches after this, replace it.
Wiper motor check
The wiper motor is installed in the water collector, under the windshield. To check it is necessary to remove the corresponding cover.
Terminal marking
The terminals on the motor are normally identified as follows:
- terminal 31 is the ground connection terminal (in general in the electrical equipment of vehicles);
- terminal 53 - receives voltage for the first wiper speed;
- terminal 53a - supplies positive current (+) for resetting the wiper blades: the motor is still energized via a sliding contact while the wipers are operating in the home position, if the driver turns off the wipers;
- terminal 53v - supplies voltage for the second wiper speed (parallel winding);
- via terminal 53e, the wiper motor is braked when moving backwards after switching off, so that the wipers do not leave their stop position;
- terminal 53s (from the relay) - supplies voltage to the electric wiper pump.
Wiper motor check
First, find out if the wiper motor is working and if the electrical supply system is in order. To find out, do the following:
- disconnect the multi-pin plug connector from the wiper motor;
- apply voltage using two auxiliary wires (+) and mass (–) from the battery to the wiper motor;
- lay one wire from the positive pole of the battery to terminal 53 or 53v;
- run the second wire from the negative pole of the battery to terminal 31 of the engine;
- now, depending on the terminal used, the motor should run in stage I or stage II. If the engine does not work, then it or its corresponding stage is faulty. Remove the wiper motor.
Checking the device of flashing light signals
The cycles for the device of flashing light signals and the emergency light signaling system are generated by a relay, the so-called flashing light sensor. The hazard warning light system is connected to a relay without a fuse. The turn signal system is protected by a fuse in the fuse box.
If the rhythm of the flashing device is faster on one side than the other, then on "fast" side, the incandescent lamp is faulty or there is an open circuit.
If other defects appear, in most cases the cause is the turn signal interrupter (flash light sensor).
The following terminal positions are indicated on the turn signal breaker:
- terminal 31 is vehicle ground (minus in the electrical equipment of all vehicles);
- terminal 49 - relay input (positive voltage is constantly applied);
- terminal 49a - relay output;
- terminal C leads to a control light on the dashboard, if there is a towing device, there may be an additional terminal C2 to signal the inclusion of the trailer direction indicators.
If you do not have a new relay, then carefully insert a thin wire between terminals 49 and 49a in the relay plug.
Attention! Be careful not to damage the sensitive relay contacts. Before inserting, bend the ends of the wire so that there are no sharp edges. Reattach the faulty turn signal breaker. Lengthen the connecting bars so that you can put the breaker back on despite the shunt.
Turn on the ignition. If the turn signal lever is now actuated, the corresponding side of the flashing light signal device lights up for a long time. By turning this unit on and off, you can generate a flickering rhythm.
If, despite the shunting, the flashing light does not light up, the turn signal switch in the electrical supply line is defective.
Checking the brake signal
If the brake light does not come on, check the fuse in the fuse box first.
If the fuse is OK, check the brake light bulbs and replace burnt bulbs if necessary.
If the incandescent lamps are working, check the brake light switch, which is located on top of the brake pedal on its rack. When the brake pedal is depressed, the push pin is pulled out of the switch. The switch contact closes and the brake light comes on.
Check the brake light switch. To do this, remove the protective cover on top of the pedal. Remove the wire end from the brake light switch.
Switch off the ignition.
Shunt both terminals in the brake light switch wire lug with a short auxiliary wire. If the brake lights now come on, the brake light switch is faulty and needs to be replaced.
Checking the rear window heater
When the rear window heating system is turned on, after some time, the area with visible tracks should be free of plaque or ice.
In case of malfunction, first check the fuse in the fuse box.
If the fuse is good, check the tight fit of the wire lug by turning it to the left and right on the rear window, if necessary, clean it of corrosion products.
If, nevertheless, the rear window heating system does not function, check the integrity of the supply wires and the operation of the switch, as well as the switching relay.
If the heating lines are broken, conductive silver lacquer helps to restore their connection. To do this, clean the damaged area with thinner or ethyl alcohol.
Glue the torn place on both sides with adhesive tape and apply silver varnish with a small brush.
Leave the varnish to dry at a temperature of about +25 degrees for 24 hours. You can warm it up with hot air. At a temperature of 130°C, the varnish dries in about 30 minutes.
Attention! Do not turn on the heated rear window until the varnish is completely dry. Do not use gasoline or other solvent to clean the damaged part.