The first step should always be to check the fuse that protects the circuit in question. The location of the fuses is indicated in the glove box and on the back of the right boot liner.
Replace the blown fuse, and after turning on the corresponding consumer, check if the fuse blows again. In this case, the cause of the burnout must be eliminated. Most often this is a short circuit, i.e. somewhere a wire or a positive voltage supply contact and ground are connected.
Second step. If, with a good fuse, the lamp does not light or the electric motor does not rotate, then you need to check the voltage supply.
Checking lamps
Remove the lamp and check the integrity of the filament. If it is burned out or the glass bulb is not sitting tightly in the base, then the lamp must be replaced.
The serviceability of the lamp can be checked by connecting it directly to the battery using auxiliary wires. In this case, the polarity of its connection does not play a role. You need to make sure that the lamp contacts are clean and free of corrosion and, if necessary, clean them and the contacts in the socket. If the lamp does not light up, then it must be replaced.
If the lamp is in order, then you need to insert it into the socket and turn it on. If the lamp does not light up, you need to check the voltage supply using a test lamp. To do this, connect one of its wires to a high-quality ground (bare metal), and the other - to the voltage supply contact in the cartridge. If the control lamp is on, but the lamp under test is not, then its connection to ground is broken. You can lay an auxiliary wire to the ground.
If there is no voltage on the current-carrying wire, i.e. the control lamp does not light, then you need to check the switch and the voltage supply circuit.
Checking the electric motor
Many functions in a car are performed by electric motors. Power windows, a sunroof, central locking, etc. work from electric motors. Each motor is controlled by a switch.
Check and, if necessary, replace the fuse for the relevant motor.
Attention: The electric motors for the power windows and the sunroof are usually protected by automatic devices that are switched off when overloaded and then switched on again after a while. When switching on again, the cause of the overload must be eliminated. It can be ice on the windows or dirty sunroof or glass guides.
If the fuse blows again, then there is a short circuit somewhere.
To determine the health of the electric motor, you need to connect its contacts using auxiliary wires (about 2 mm in diameter) directly with AB, observing the polarity. All electric motors in the vehicle run on 12 volts. If the engine now runs normally, then there is a problem with the voltage supply circuit. If the motor rotates slowly, its contact brushes may be worn out and must be replaced.
If the engine is running, then from the diagram you need to determine which wires supply voltage to it, how the switch works, and whether the ignition should be turned on.
Check the motor live wire with a test lamp with two sharp prongs to pierce the wire insulation if necessary. The connecting contacts of the electric motors are marked as standard.
- contact 32 - ground connection;
- pin 33 - positive voltage supply.
Motors that rotate in two directions, such as power window motors, have two positive voltage contacts:
- pin 33L - to rotate the engine to the left;
- terminal 33R - to rotate the motor to the right.
Attention: The wiper motor has its own terminal designations.
If there is no voltage on the motor, then the voltage supply circuit is faulty. In this case, to troubleshoot, you need to use the wiring diagrams. Due to the high current consumption, relays are often built into the voltage supply circuit, the verification of which is described below. If everything is in order in the power circuit, check the switch.
If there is a wire break, it is easier to install a new wire than to look for a break in the old one.
Checking the operation of the switches (switches)
Most electrical consumers are turned on and off by switches that are operated by hand. However, there are also switches that operate automatically. These include, for example, switches for oil pressure and brake fluid level warning lights.
The task of any switch is to close and open the current circuit. Some switches open the ground circuit, others open the positive voltage circuit.
Checking lamp and motor switches
Remove the switch.
A simple switch has two contacts for wires, one of which is energized constantly, and the other after the switch is activated. There are also switches with multiple contacts (switches). The schemes of operation of such switches, i.e. supply voltage to them, are indicated in the electrical diagrams. If necessary, turn on the ignition.
Use a test lamp to check if the switch is receiving voltage. If it exists (the lamp is on), then turn off the switch and check if voltage appears on its output contact. If it is, then the switch is working properly.
If there is no voltage at the input contact, then there is a break in the voltage supply circuit, which must be eliminated by installing a new wire if necessary.
Checking the switches-sensors
The sensors-switches include the following: switches for oil pressure control lamps, brake and coolant levels.
Connect an ohmmeter to the switch contacts, disconnecting the wires from them.
Attention: Switches that are screwed into the cylinder block, as a rule, do not have a wire for connecting to ground - this is the switch housing.
With the switch closed, the ohmmeter should show a resistance close to 0 ohms.
The easiest way to check the operation of the coolant level and brake fluid level switches is to disconnect the wire from the switch with the ignition on and connect this wire to ground. If the control lamp on the panel of devices lights up, the switch is faulty.
The oil pressure warning light switch works differently: when the engine is off, its contacts are closed (control lamp on), and when a certain oil pressure is reached, the switch opens.
Relay test
Relays are installed in many circuits. The switching relay works like a switch: when the consumer switch is activated (activated by hand), then the relay receives a command to apply voltage to the consumer. It is possible, of course, to supply current to the consumer from the battery directly through the switch, but for consumers that consume high current, the relay is turned on so as not to overload the switch or to provide the shortest voltage supply path. In addition to these switching relays, there are functional relays, such as the wiper/washer relay.
Checking the switching relay
When the corresponding consumer is switched on, the relay is activated, i.e. under the action of the control current, the coil inside the relay closes the contacts through which the main one passes, «worker» current that passes to the consumer.
The easiest way to check the operability of the relay is to replace it with a known good one. The car does not always have a spare relay. If not, then follow the steps below. The following contact designations are for serially installed relays.
Remove the relay from its socket.
Turn on the ignition and the corresponding switch.
Check with a voltmeter for voltage on pin 30 in the relay socket by connecting it between ground and pin 30. If there is no voltage, then check the voltage supply circuit to it from the battery and repair the open.
Make a jumper wire by stripping the two ends of the insulated wire.
Connect pins 30 and 87 with this jumper (relay output contact). This simulates the operation of a working relay. The pin arrangement is usually marked on the relay itself or on the relay socket. If the consumer is activated when the jumper is installed, then it can be concluded that the relay is not working.
If the consumer does not work, then you need to check the connection of the consumer to the ground. Then you need to check the wires coming from terminal 87 to the consumer.
If necessary, replace the relay with a new one.
Attention: If the malfunction appears from time to time, then it is most likely related to the relay. In this case, the contact departs and connects randomly, and the relay also operates irregularly. You can tap on the relay housing when it is not working. If the relay works after tapping, then it is faulty and subject to.
Wiper motor check
The wiper motor is located in a recess under the windshield. Remove the cover to check.
Designation of motor contacts:
- pin 31 - ground connection (throughout the electrical system);
- terminal 53 supplies voltage for the first wiper speed;
- contact 53a supplies voltage for the wiper home position: there is voltage on the motor from the sliding contact as long as the wiper is in the idle state, i.e. when the driver turns off the windshield wiper;
- contact 53v supplies voltage for the second wiper speed;
- Via terminal 53e, the wiper motor is braked during reverse operation after switching off, so that the wiper arms do not jump out of their original position.
Wiper motor check
First of all, you need to find out what is faulty: the motor or the voltage supply circuit. To do this, do the following:
Disconnect the plug from the wiper motor.
Using two auxiliary wires, connect the battery to the wiper motor: connect the positive wire to terminal 53 or 53c, connect the negative wire to terminal 31. The wiper motor should now run at speed 1 or 2. If this is not the case, then the motor or the corresponding circuit is faulty.
Checking the brake signal
If the brake light does not come on, check the fuse.
If the fuse is good, check the bulbs and replace if necessary.
Check the brake light switch by removing the cover over the pedals. Remove the plug from the switch.
Turn on the ignition.
Bridge the contacts in the brake light switch plug with a short auxiliary wire. If the brake light now comes on, the switch is faulty and needs to be replaced.
If it doesn't light up, check your headlights.
Rear window heating test
When the heated rear window is turned on, the area with the heating filaments is freed from fogging and ice after a while.
In the event of a malfunction, first check the fuse.
If the fuse is OK, check the tightness of the plugs on the left and right on the rear window, if necessary, clean the corrosion.
If the heated rear window still does not work, check the wires, switch and relay.
1 - damaged wire;
2 - adhesive tape;
3 — repaired area.
If the heating wires are damaged, a conductive silver paste must be used to restore contact. Before applying it, clean the damaged areas with a solvent or alcohol.
Tape the damaged area on both sides with adhesive tape and apply silver paste with a thin brush.
The paste should dry for about 24 hours at 25°C. You can use a hair dryer. At +150°C, the paste dries in about 30 minutes.
Do not turn on the glass heating until the paste is completely dry. Do not use gasoline or other mineral solvents to clean parts.