There are two types of circuit damage: open circuit and short circuit.
When the circuit breaks, the circuit opens and power is not supplied to the electrical appliance. Sometimes a break is very difficult to detect due to the fact that the body of the connecting block hides oxidized contacts or incorrect connection. In addition, a break can be detected when the pads or wiring harness are wiggled. This must be taken into account if there are signs of a break or intermittent operation of the appliance.
A short circuit is an unacceptable connection of a part of a circuit with «weight» or another part of the circuit. Usually a short circuit leads to a blown fuse or spontaneous switching on of electrical appliances.
After repairing the 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 performed, but also the correctness of the diagnostics performed when troubleshooting.
Continuity Check
The integrity of the circuit is checked with a multimeter in ohmmeter or continuity mode. The multimeter leads are connected to the ends of the circuit under test. If the circuit is intact, then the multimeter in the continuity mode beeps (see multimeter instruction manual). In ohmmeter mode, if the circuit is intact, the resistance will be minimal, and if the circuit is open, the resistance will be very large (strive for infinity).
Short circuit search
If there is a suspicion of a short circuit in any section of the circuit, disconnect this section from the rest of the car's wiring by disconnecting all its connecting blocks. We connect one output of the multimeter in the mode of ringing the circuit to the tested section of the circuit, and the second to «mass» car. If the circuit is closed, then there is a short circuit in this section of the circuit, which must be found by carefully examining the entire section of the circuit (wiring harness).
If a short circuit has occurred due to damage to the wire insulation, then it can be eliminated by restoring the wire insulation with electrical tape.
Often the cause of a short circuit is a strong oxidation of the contacts in the connecting 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.