To diagnose and fix electrical faults in vehicles, it is crucial to thoroughly test the wiring and connectors. The wiring in a vehicle is made up of multiple copper strands surrounded by an insulating thermoplastic layer. The copper acts as a conductor of the electrical current, while the outer layer protects the strands from heat, moisture, and shorting. Wires are organized in looms and connectors, which connect sections of wire to corresponding pins on a plug. Damage to the protective layer can cause moisture to enter the copper strand, causing high resistance for the electrical current. Proper testing of electrical integrity is essential to ensure the safety and efficiency of the vehicle’s electrical system
How to back probe ?
Probing back probing is a popular method in automotive diagnostics, involving inserting a multimeter with a pin or back pin probe next to a wire on the rear of a connector to investigate wire integrity. This method doesn’t damage the wire’s insulating layer or terminals and doesn’t require removing any connectors. To carry out an effective back probe test, remove the back cover from the connector, slide the probe down the wire side, and insert the probe at least two points on the wire to determine the terminal orientation.
Diagnose a faulty wire
To identify faults in a suspect wire, three main circuit failures can be identified: short, open, or high resistance. High resistance is usually caused by corrosion of internal copper strands, poor terminal contact, or overheating. To test for resistance, use a multimeter to check continuity. Conduct a voltage drop test to diagnose high resistance, ensuring the vehicle is running and the battery under load. Consult manufacturer specifications before diagnosing an open circuit.
Diagnosed an open circuit
Open circuits on multimeters are caused by complete wiring break, severe corrosion damage, external overload, or wear and tear over time, or poor terminals.
Diagnose a short circuit
Circuits touching each other can cause electrical current to flow through a different path, causing a surge. This can occur when a damaged wire contacts a damaged ground or low reference wire, or when a current carrying wire contacts another out of the intended circuit path. To test for a short, use a multimeter. Perform a continuity test between the native side of the battery and the affected wire, ensuring no continuity between the wire and the battery ground. If resistance is displayed, the wire is damaged.
Repaired damaged wiring
To repair damaged wiring, use precision side cutters to cut each side of the wire and strip each end using wire strippers. The repair methods vary depending on the space and amount of sack. A crimp sleeve is an easier method, but use a good crimping tool and a heat shrink cover. If the wire is broken, solder it back together tightly, applying soldering iron and allowing it to flow all over the connection for a solid and reliable joint.
Repaired damaged terminal
Damaged wiring is only half of a faulty wire. To check for terminal tension and connector corrosion, remove the connector and inspect both ends for any buildup or discoloration. Terminal tension tests require the correct size drag tool and the correct tools. Remove the connector from the corresponding plug, remove the back cover, and remove any secondary lock or terminal position assurance device. Different connectors have different sizes and locking mechanisms, so use the correct terminal removal tool and know which side to approach. Re tension the faulty terminal or replace it with a new one.