Wiring diagrams of the Iveco truck. A conventional electrical circuit consists of an electrical element, switches, relays, motors, fuses, circuit breakers, wires and connectors that connect the electrical element to the battery and body. Before attempting to identify the source of the malfunction, examine the appropriate electrical diagram to get an idea of the elements installed in this circuit. The range of possible sources of malfunction can be narrowed if you check the functioning of other elements entering the given circuit. If several elements or circuits fail at the same time, then the problem is obviously the fuse common to these circuits or elements, or the contact with the body.
Electrical problems are usually caused by simple causes, such as loose or rusted connectors, a lack of contact with the body, blown fuses, a melt-blown jumper, or a faulty relay. Visually check the condition of all fuses, wires and connectors in the failed circuit before proceeding to check the remaining elements. Use electrical circuitry to determine which of the end clamps to check for the source of the fault. The main tools needed to detect the source of the malfunction are a tester or voltmeter (a 12 volt bulb and a pair of wires with probes at the ends can also be used for some checks); an ohmmeter; a battery and a set of wires with probes, a casing puncture, preferably with a circuit breaker or a fuse, which is used to bypass the wires or elements being checked. To detect the cause of unreliable operation of any of the elements (usually due to poor connection or contamination of contacts, as well as damaged insulation), you can test the shaking of the wires. It is necessary to shake the wire with your hand to check if the fault occurs when the wire is moving. In this way, you can narrow the range of possible sources of failure to some kind of wire.