Checking and repairing electrical circuits (Opel Zafira A)

Contents: Checking the integrity of the circuit ⬇ Short circuit detection ⬇ Wiring repair ⬇

When diagnosing circuits and repairing electrical equipment, it is necessary to carefully inspect the wiring, check the correctness of the connections, the absence of burnt, frayed or pinched wires, and ensure that the wires do not come into contact with sharp edges or parts subject to heating to high temperatures (for example, the exhaust manifold). Damaged wire insulation must be restored (for example, with electrical tape) or replace the wire.

There are two cases of circuit damage: open circuit and short circuit.

When a break occurs, the circuit is disconnected and no power is supplied to the electrical appliance. Sometimes a break is very difficult to detect because the casing of the terminal block hides oxidized contacts or an incorrect connection. A break can also be detected by shaking the blocks or the wiring harness. This must be taken into account if there are signs of a break or inconsistent operation of the electrical appliance.

A short circuit is an unacceptable connection of a part of a circuit to the "ground" or another part of the circuit. Typically, a short circuit results in a blown fuse or spontaneous switching on of electrical appliances.

After repairing the electrical wiring, it is necessary to check the circuit by turning on the electrical appliances included in this circuit. This confirms not only the correctness of the repair, but also the correctness of the diagnostics performed when searching for a malfunction.

Checking the integrity of the circuit

The integrity of the circuit is checked in the ohmmeter mode. The multimeter leads are connected to the ends of the circuit being checked. When using the circuit continuity mode, if the circuit is intact, the multimeter emits a beep signal (see the multimeter operating instructions). When using the ohmmeter mode, if the circuit is intact, the resistance will be minimal, and if there is an open circuit in the circuit, the resistance will be very high - tending to infinity.

Short circuit detection

If there is a suspicion of a short circuit in any section of the circuit, then disconnect this section from the rest of the car's wiring, disconnecting all its connecting blocks. Connect one terminal of the multimeter in the circuit continuity mode to the section of the circuit being checked, and the second to the "ground" of the car. If the circuit turns out to be closed, then there is a short circuit in this section of the circuit, which must be found by carefully inspecting the entire section of the circuit (wiring harness).

If a short circuit occurs due to damage to the wire insulation, it can be eliminated by restoring the wire insulation using electrical tape.

Often the cause of a short circuit is severe oxidation of the contacts in the connector blocks. In this case, it is necessary to carefully clean or replace the contacts. Before connecting, it is better to treat the contacts with a special conductive grease.