First of all it is necessary to check the fuse, because all circuits are protected by fuses. The layout of the fuses in the mounting block is located on the cover of the fuse box.
A blown fuse must be replaced. After installing a new fuse, it is necessary to turn on the device and check if the fuse has blown again. In this case, it is necessary to look for a malfunction in the circuit. Usually the cause is a short circuit. This means that somewhere in the circuit or inside the device, the positive and negative poles are closed together.
Note: The heated rear window as well as the electric motors for the power window, the central locking device and the air conditioner are equipped with thermal relays as fuses, which are switched off in the event of an overload and can be switched on after a short time.
Secondly: If the fuse is OK, and the incandescent lamp does not light, or the electric motor does not start, you need to check the power.
Checking electric motors
The level of comfort in the car is largely created by numerous electrically driven devices. These include, for example, the power window, the sliding sunroof, the central locking device, the electrically operated aerial.
The electric motor is started by a switch, in most cases by hand. If there is a motorized antenna, it is controlled automatically by the radio receiver.
Check motor fuse. Replace if necessary.
Note: The electric motors for the power window, the central locking device and the air conditioner are equipped with an automatic fuse. Before turning on the machine after it has been triggered, the cause of the overload must be eliminated. Causes such as icing on windows and door locks or soiled sliding glass guides can be examples of this.
If the new fuse blows immediately, the cause is a short circuit.
To find out if the fault is in the electric motor itself, you need to connect it with auxiliary wires (diameter 2 mm) directly with the battery. Positive wire with positive pole, ground wire with ground contact on the motor. All onboard electric motors are powered by 12... 14 V. If the motor is now running, the malfunction is related to the power supply.
Note: An electric motor running at low speed or intermittently may have worn carbon brushes as the cause of the malfunction. In this case, they must be replaced.
If the motor is running, use the wiring diagram to find out which wire it has current-carrying when the switch is turned on with the ignition on.
Using a test lamp, check the current-carrying wire on the electric motor. Since the current of automobile electric motors is large, you can use a test lamp with a conventional incandescent lamp for this. These indicator lamps have tips that can be used to pierce the connecting wire. This is the easiest way to check voltage. Reversible electric motors, such as power windows, have two positive contacts.
Attention: The wiper motor has a special connection. Check it out in the corresponding section.
If there is no voltage on the electric motor, the power supply is damaged. Find the damage according to the diagram and fix it. Due to the high current strength, the electric motors are powered through a relay. Check the relay, see the appropriate section.
If no fault is found, check the switch.
If the wire is damaged, then it makes sense to replace it, because. elimination of the defect is not feasible.