Fault diagnosis onboard electric equipment

The structure of a typical electrical circuit may include the main electrical element, various switches, relays, motors, fuses, fuses or circuit breakers related to this element, wiring and connectors that serve to connect the main element of the battery and the "weight" of the body. To facilitate troubleshooting of electrical circuits in the manual are circuit diagrams and wiring diagrams.

Before you start working on troubleshooting a circuit, carefully study the corresponding scheme that as clearly as possible to imagine its functionality. Circle troubleshooting usually by gradually narrows the definition and exclusion of well-functioning elements of the same circuit. With the simultaneous failure of several elements or outlines the most likely cause of failure is a blown fuse or a violation of the relevant ground (various chain in many cases may be closed by one fuse or earth terminal).

Electrical failure is often explained by simple reasons, such as corrosion of the connector pins, failure of fuses, blown fuse, or damage to the relay. Visually check the condition of all safety locks, wires and pin connectors circuit before proceeding to a more detailed inspection of serviceability of its components.

In the case of applications for troubleshooting diagnostic tools, plan carefully (according to the wiring diagrams), in which the point of the circuit and the sequence in which the device must be connected to most effectively detect faults.

The main diagnostic devices include electrical circuits tester or voltmeter (you can use a 12-volt test light with a set of connecting wires), LED open circuit (probe), which includes a lamp, its own power supply and a set of connecting wires. In addition, you should always have a set of wires in the car to start the engine from an external source (other car battery) equipped with terminals of type "crocodile" and preferably a chopper circuit. They can be used for bridging and connecting various electrical components in the diagnosis circuit. As already mentioned, before proceeding to the verification of the circuit using the diagnostic equipment, identify schemes where it is connected.

Check for voltage held in the event of an electrical circuit. Connect one of the wires of electrical circuits or the tester to the negative terminal of the battery or to a well-grounded point of the car body. Another wire tester connected to the terminal connector circuit under test, preferably closest to the battery or fuse. If the warning light tester lights, the power supply in this segment of the chain there, confirming serviceability of the connection between this point of the circuit and the battery. Proceeding in the same manner, examine the rest of the circuit. Detection of violations of voltage indicates a fault between a given point of the circuit and the last of the previously tested (where it was the power supply). In most cases, the cause of failure is weakening pin connectors and damage the contacts themselves (oxidation).

Finding fault location.

One way to find the short circuit is to extract the fuse and wiring instead lamp or voltmeter probe. The tension in the chain should be absent. Pulled wiring, watching the lamp-sampler. If the light starts blinking, somewhere in the wiring harness is the closure of the "masses" may have caused grinded wire insulation. A similar test can be carried out for each of the components of the electric circuit by incorporating the respective switches.

Check the reliability of the contact with the "masses."

Disconnect the battery and connect one wire lamp probe having a self-contained power source, to a point with a known good contact with the "masses." Another lamp wire to connect the suspected harness or connector pins. If the lamp lights up, the contact with the "masses" in order (and vice versa).

Check for broken wire detection circuit continuity. After a power circuit, check it with a lamp-sampler with independent power supply. Connect the probe to both ends of the chain. If the warning light comes on, there is an open circuit. If the lamp is not lit, it indicates the presence of a chain break. Similarly, you can check the power switch and connecting the probe to the contacts. While translating the switch in the "On" lamp should illuminate the probe.

Locating the break.

When the diagnosis is suspected of having an open section of the circuit to visually detect the cause of the problem is rather difficult, as inspection terminals on the appearance of corrosion or violation of the quality of their contacts is difficult because of limited access to them (normally closed terminal connector housing). Sudden twitching body harness pads on the sensor itself, or harness in many cases leads to the restoration of contact. Keep this in mind when trying to localize the causes of failure is suspected of having an open circuit. Instability arises failures may be due to oxidation of the terminals or violation of the quality of contacts.

Troubleshooting of electrical circuits is not a difficult task, provided a clear idea of what an electric current is supplied to all consumers (lamps, electric motor, etc.) from the battery through the wires through switches, relays, fuses, fusible links, and then returns in battery through a "mass" (body) of the car. Any problems associated with electrical failure can be caused by the cessation of feeding them electric current from a battery or return current to the battery.