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 located under the fuse cover in the glove box and on the back of the right side lining of the luggage compartment (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 immediately blows 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 test: if, with a good fuse, the incandescent lamp does not light or the electric motor does not work, it is necessary to check the presence of supply voltage.
Incandescent lamp test
Remove the lamp and inspect. If the incandescent bulb is burned out or is loose 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 is to the current-carrying connector, and the other is 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 the lamp 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, install a jumper wire from ground to the lamp socket. In this case, the lamp should light up.
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.
Otherwise, the hanging module must be checked.
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 or electric central locking. Each electric motor is turned on with a switch if necessary, in most cases by hand.
Check the fuse of the relevant electric motor, replace the fuse if necessary.
Application: the electric motors of the power window and the drive of the roof panel are usually equipped with a circuit breaker, which, when overloaded, opens the electrical circuit, and after a while closes it again. Before switching on again, the cause of the overload must be eliminated. It may consist in the freezing of windows or contamination of the window guide rails.
If the fuse blows again immediately, there is a short circuit.
To unequivocally determine whether the 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 battery or to the positive and negative connectors located in the engine compartment. 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 engine is running, look at the wiring diagram to determine which wire supplies power to the engine 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. Connectors of electric motors are designated by unified numbers with small numbers:
- terminal 32 is the ground connector (-);
- terminal 33 is positive (+) connector.
Reversible electric motors, such as power windows, have two positive connections. In such motors, terminal 33L is energized to make the motor rotate to the left, and terminal 33R is energized to make the motor rotor to rotate to the right.
Attention: The wiper motor has a different terminal designation, see the relevant chapter.
If there is no voltage to the 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 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.