What are the problems that automobile wiring harness often appears?
Automobile wire harness refers to the component of the connecting circuit formed by a wire harness, which is formed by pressing the contact terminals made of copper and crimped with wires and cables.
Hulk insulator or metal hulk is applied outside and bundled with a wire harness. In practical application, the automotive wiring harness is easy to causes extreme safety problems once failure occurs due to high use intensity, bad working environment, substandard production quality and other problems. So the use of an automotive wiring harness is prone to what problems?
An automotive wiring harness refers to the component that constitutes the connection circuit. It is made by crimping copper terminals and connecting them with wires and cables.
The sheathed insulation or metal sheath is usually installed externally and is bundled with the wire harness. In practical applications, due to factors such as high usage intensity, harsh working conditions, and substandard production quality, once the automotive wire harness malfunctions, it can easily cause serious safety hazards. So, what problems are likely to occur when using automotive wire harnesses?
The cable bundle is worn
Automobile movement will inevitably be jolted, especially the chassis wiring harness, wear risk is relatively large. When the friction breakdown down the wire harness and suspension, it will cause lashings, resulting in the failure of the electronic stability system.
Wear and tear of the wiring harness is one of the most common problems, mainly caused by mechanical friction and environmental erosion. The specific causes of wear are as follows:
- The wiring harness comes into long-term contact and friction with the metal components of the vehicle body (such as the frame, edge of the sheet metal), especially the vibrations during vehicle operation will aggravate the wear, resulting in the damage of the outer insulation layer.
- Improper fixation of the wiring harness during assembly (such as loose or missing clips) causes the wiring harness to collide and rub against other components during movement.
- Foreign objects (such as gravel, sand) entering the wiring harness layout area repeatedly scrape the surface of the wiring harness due to vehicle vibrations.
Wire feed water
The automotive wiring harnesses are mostly located in areas prone to moisture contact such as the engine compartment, chassis, and doors. Water ingress is quite common:
- The sealing strips (such as those on the doors and the engine hood) become aged, causing rainwater to seep into the gaps or interfaces where the wiring harnesses are located.
- The wiring harness connectors have poor sealing (such as damaged waterproof gaskets or incomplete clamping of the connectors), allowing water vapor to enter during washing or when driving through water.
- The outer layer of the wiring harness is damaged (such as wear or cracking), allowing moisture to directly enter the internal wires.
If the sealing process is not properly controlled in the production of the harness, the body control module (BCM) or the wiring harness at the connection between the BCM and the body a-pillar may be damaged due to water inflow.
Burnt and ablated wire harness
For the automobile, such as installed in the engine, exhaust pipe, water pipe and other heat sources near the wiring harness, often due to the lack of a clip fixed and burned, scorched, resulting in electrical equipment failure, eventually cause spontaneous combustion.
Such problems are usually related to circuit overload and short circuit, and they are relatively serious faults. Common causes of burning include:
- Circuit short circuit (such as after the wire harness wears out, the wire contacts the vehicle body, or there is an internal short circuit in the electrical appliance), resulting in an instantaneous excessive current that exceeds the carrying capacity of the wire harness, causing the wire to heat up and burn through the insulation layer, and even melting the metal core.
- Mismatch between the cross-sectional area of the wire harness and the power of the electrical appliance (such as when modifying, using thin wires to connect high-power equipment), long-term overloading leads to the wire overheating, gradually burning out.
- Poor contact (such as loose connectors), with excessive resistance at the contact point, generating high temperature when powered on, igniting the surrounding wire harness or plastic components.
Poor wire harness contact
The bad connector of the wire harness assembly is a common failure mode of the engine wire harness. Too many bad contact problems occur in the connector, such as poor sheath quality, poor assembly process, unreasonable coating setting, and terminal oxidation is one of the reasons. Poor wiring harness contact does not appear to be fatal. But the pitfalls are many, and it’s easy to detract from the experience. Things like headlights not coming on, engines not starting, and glass lifters not working can be caused by it.
The wiring harness is connected through components such as plugs, terminals, and connectors. Poor connection can directly affect the smoothness of the circuit:
- Loose plugs/terminals (if not properly inserted during assembly or due to long-term vibration causing the snap fasteners to come off), resulting in reduced contact area or intermittent disconnection.
- Accumulated dust, oxidation, or rust inside the connector (especially in humid environments) can form contact resistance and hinder current transmission.
- Deformed terminals (such as improper force during insertion or due to collision), unable to closely fit with the corresponding plug.
Wire harness fracture
Wire harness fracture is a common fault model of automobiles, and the reasons can be simply listed as: the branch design of wire harness is too short, the manufacturing of wire harness is not standard, and the wire harness is twisted during assembly. Because some line speeds are subject to warping, this kind of fracture risk is often difficult to avoid.
The breakage of wiring harnesses is mostly caused by mechanical stress or fatigue damage. It is commonly found near moving parts. The specific reasons for breakage include:
- The wiring harness is overly tightly arranged or excessively bent (for example, the door wiring harness is repeatedly bent during the operation of the switch), and long-term stress leads to fatigue of the wire metal, resulting in gradual breakage.
- External force pulling (such as mistakenly pulling the wiring harness during maintenance, or the chassis wiring harness being caught by foreign objects), exceeding the strength that the wire can withstand leads to breakage.
- Ageing of the wiring harness (especially in high-temperature and oil-contaminated environments), the brittleness of the wire increases, and even slight vibration can cause breakage.
Conclusion
The problems of automotive wiring harnesses are mostly related to environmental factors (wear and moisture ingress), circuit abnormalities (overload and short circuit), connection reliability (looseness and oxidation), and mechanical stress (fracture). During daily use, regular checks on the fixation of the wiring harness, the sealing condition, and the cleanliness of the connectors can help prevent the occurrence of these issues.
Avoiding unauthorised modifications of non-compliant circuits can also effectively reduce the likelihood of such problems. If any abnormalities are detected in the wiring harness (such as odours, abnormal sounds, or electrical malfunctions), prompt repair or replacement is necessary to prevent the expansion of the fault.
Zhejiang Lianhe Electronics Co., LTD., specialising in inline production line, board-to-board, the line to board, automobile connector, wire harness and other products, welcome to visit our official website https://www.lhecn.com/contact-us/ for inquiry
