Troubleshooting the Electrical System [Toyota 4Runner N120]

The electrical circuits of a car include a consumer, switches, relays and wires connected according to the attached diagram (see below). Before you start looking for a fault, you should study the diagram and determine the possible source of the fault. For example, the task of finding a fault is significantly easier if you can check the serviceability of other consumers directly or indirectly connected to the suspected circuit.

If there is a failure of several consumers, then the most likely cause is a broken connection to ground or a blown fuse. As a rule, electrical equipment failures are caused by loose or corroded contacts, a blown fuse or a melted jumper. Troubleshooting is usually performed using a tester (voltmeter) or a test lamp, which are connected between the section of the faulty circuit and a well-cleaned ground.

By connecting a tester or a lamp in series along the circuit, you can identify a faulty section, which is detected by a loss of voltage or the lamp going out.

To find a short circuit in the wires, remove the fuse of the circuit being tested and connect a lamp or voltmeter to the gap. A short circuit with ground is indicated by the lamp lighting up when the wires are swung from side to side (the tester should show voltage). When checking, please note that some consumers receive power when the ignition key is in the Accessories or Run position.

To check the reliability of the connection to ground, connect through an ohmmeter (or via a control lamp with a battery) the tested wire connection to the ground and a well-cleaned section of the ground. If the ohmmeter shows a circuit (or the lamp will light up), then the ground connection is reliable. Otherwise, the ground contact is broken. Keep in mind that in most cases, the ground serves as a return current conductor connecting the circuit to the negative pole of the battery. Therefore, a broken ground connection, or a break in the return current circuit to the battery, can be the main cause of failure.

The information was taken from a web portal: Toyotaman.ru