The first step is always to check the fuse if the electrical circuit is protected. The location of the fuses is shown in the table on the cover of the fuse box, see also Section Replacing fuses.
If necessary, replace the defective fuse, and after switching on the electrical consumer, check whether the fuse has blown again. In this case, you must first find and eliminate the malfunction, as a rule, we are talking about a short circuit. This means that in some place, maybe also inside the device, ground and plus are connected to each other. Second step: If the lamp does not light or does not work with a good fuse, check the voltage supply.
Checking lamps
1. Remove and inspect the lamp. If the filament is burned out or the glass bulb in the base is loose, replace the lamp.
2. To determine the health of the lamp, proceed as follows: One positive wire and one ground wire are connected directly to the battery poles and connected to the lamp. It does not matter how the wires are connected to the lamp. If the lamp does not light, replace the lamp.
Note. Make sure that the contacts on the lamp and in the socket are not corroded. If necessary, clean the contacts with sandpaper.
3. If the lamp is OK, insert the lamp and turn it on. If the lamp does not light, check the voltage supply with an indicator. To do this, attach a voltage indicator to the ground. This means: One indicator cable must be connected to a reliable ground on the engine (bare metal) or directly connected to the ground terminal of the battery. Connect the other positive indicator probe either to the plug or to the cable. If the indicator lights up, but the lamp still does not light up, the mass supply to the lamp is interrupted. To check, connect the auxiliary earth wire to the earth of the lamp socket. The lamp should light up.
Note. There are lamps that only have a conductive wire, such as parking light, interior lighting. These lamps are connected through their housing directly to the vehicle ground.
4. If there is no voltage on the conductive cable of the lamp, i.e. the indicator does not light up, it is very likely that the switch is faulty. Check the switch for current flow.
Checking electric motors
1. More and more comfort functions are carried out in the car by small electric motors. This applies, for example, to power windows, sunroof, electric central locking device or electric aerial drive.
2. Each motor is turned on with a switch if necessary, in most cases by hand. The electric antenna is controlled automatically by the radio receiver.
3. Check the fuse of the relevant electric motor, replace if necessary.
Note. On power windows and the central locking device, the cause of the overload must be eliminated before reactivation. This may be icing on the windows or locks, as well as contamination of the glass guides.
4. If the new fuse blows immediately, then there is a short circuit.
5. To determine if the fault is in the motor, connect 2 auxiliary cables to it (diameter 2 mm) directly from the battery. Positive cable to the positive pole, earth cable to the earth pole of the electric motor. In case of doubt, determine the location of the poles according to the diagram. To do this, the electric motor must be removed. All electric motors in the car are powered by the on-board network (12-14 V). If the motor now runs normally, the fault is in the wiring.
Note. Too slow or erratic motor operation can be a sign of worn carbon brushes. In this case, replace the brushes.
6. If the motor is running, determine from the diagram which wires supply voltage to it if the switch is turned on or the ignition is preliminarily turned on.
7. Check the conductive wire on the electric motor using an indicator. Since a large current flows in electric motors, you can use the old indicator with an incandescent lamp. The indicator has sharp probes that can be inserted into the cable. This way you can check the voltage the easiest way. Motors that rotate right and left, such as power window motors, have two positive poles.
Attention! Check of the screen wiper motor see in the Chapter Removal and installation of the front wiper motor.
8. If no voltage is applied to the motor, then the wiring is faulty. Find and fix the problem according to the scheme. Electric motors, due to the need for high current, as a rule, have additional switching relays. Checking see Chapter Removal and installation of the front wiper motor.
9. If no fault is found, check the switch.
10. If the cable is faulty, it is more expedient to lay a new one, since it is very difficult to find the place where the cable breaks.