As a core component of the automotive electrical system, the wiring harness is like the "neural network" of the vehicle, and its functional integrity directly determines the safety of the entire vehicle's operation. Data shows that the total length of the wiring harness of an ordinary household car can reach over 1,500 meters. Once such a complex system malfunctions, rework is by no means a simple disassembly and assembly operation, but a comprehensive test of precision, craftsmanship and standards, and its significance runs through the entire life cycle of the vehicle.

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I. Core Technical Requirements for Wire Harness Rework

Wire harness rework must strictly follow millimeter-level operation standards. Any deviation in any link may lead to serious consequences. Among them, wire stripping and crimping, as basic processes, have particularly strict requirements for process accuracy. During the wire stripping process, the operation requires precise control of the stripping depth: excessive depth will damage the conductor of the wire and deteriorate its electrical conductivity. If it is too shallow, the stability of the joint contact cannot be guaranteed, which may easily lead to abnormal signal transmission. The operators need to use professional wire stripping equipment to complete the operation with a precision similar to that of surgical operations, ensuring that the stripping range of the insulation layer of the conductors and the exposed length of the conductors fully comply with the technical specifications. ​

The crimping process also does not allow for the slightest error. Excessive pressure force can easily cause deformation of the terminal metal and affect the stability of the connection structure. Insufficient force will increase the contact resistance, causing local heating and even posing a short-circuit hazard. To ensure the quality of crimping, the industry generally adopts high-precision crimping equipment worth hundreds of thousands of yuan. Through digital control, precise matching of crimping force, crimping depth and terminal deformation is achieved, eliminating process deviations at the equipment level. ​

Conduction testing is a key step in verifying the quality of rework. After rework, the wiring harness needs to complete the conductivity test at over a hundred test points. If any test point shows an abnormality, the entire wiring harness system needs to be re-examined. This process has extremely high requirements for detection accuracy and personnel concentration. It is necessary to verify the conduction status of each circuit one by one through professional detection instruments to ensure there are no open circuits, short circuits or poor contact problems. Its level of precision far exceeds the conventional manufacturing inspection standards. ​

II. Potential Risks and Avoidance Measures in Wire Harness Rework

(1) The hidden effects of component aging and environmental interference

Most people have a misconception about rework that it should be restored exactly as it is. In fact, when reworking wire harnesses, special attention should be paid to the aging of components. During the use of the wiring harness, the insulation layer may develop tiny cracks that are hard to detect with the naked eye. If such hidden damages are not dealt with in time, they will gradually expand over time and eventually lead to insulation failure. Therefore, during the rework process, all suspicious components must be replaced instead of merely repairing visible fault points. ​

The impact of environmental factors on the quality of rework is also easily overlooked. Changes in humidity can cause thermal expansion and contraction of the wire harness material, while temperature fluctuations can affect the adhesion and stability of the insulating tape, thereby damaging the overall structure of the wire harness. To avoid such risks, professional rework workshops are all equipped with constant temperature and humidity control systems, keeping the environmental humidity within the standard range of 40% to 60% and the temperature within 23±2℃, minimizing the impact of environmental interference on the quality of rework to the greatest extent. ​

(2) Technological challenges brought about by vehicle model differentiation

There are significant differences in the wiring harness layout among different brands and models. For instance, the wiring harness design specifications, interface standards and wiring paths of Volkswagen and BMW models are completely different, which poses extremely high demands on the professional capabilities of the rework personnel. The operators need to be proficient in the wiring harness diagrams of various vehicle models, clearly understand the fixing methods, protection standards and connection requirements of wires in different areas, and avoid operational deviations during rework due to differences in vehicle models. ​

III. Quality Control System after Wire Harness Rework

(1) Quality risk prevention and control in the crimping process

Terminal crimping is a high-risk step in the rework of wire harnesses, mainly with three quality risks: First, secondary crimping can easily cause fatigue deformation of the terminal metal material, reducing its electrical conductivity and structural strength; Second, during the rework operation, the copper wire inside the terminal may break or be damaged, directly affecting the current-carrying capacity of the wire harness. Thirdly, repeated crimping will damage the surface coating of the terminal, accelerate the oxidation and corrosion process, and shorten its service life. ​

At the process control level, the key dimensions such as the crimping height and width of the terminals after rework are difficult to be consistent with those of the first crimping, which can easily affect the connection reliability. What is more serious is that metal debris may remain during the rework process, posing a potential short-circuit risk. If these problems are not controlled in time, they may cause safety accidents such as poor contact, local overheating and even fire in subsequent use. Therefore, the industry strictly limits the number of times wire harnesses can be reworked, usually requiring no more than two reworks for the same part. It also establishes a complete set of rework process norms and inspection standards to ensure that each crimping process meets quality requirements. ​

(2) Standardized procedures for appearance inspection

The appearance inspection of the wire harness after rework must follow a strict standardized system, mainly covering five core dimensions: First, the surface of the wire harness should have no obvious scratches, indentations or deformations, the wires should be neatly arranged, and there should be no cross-entanglement phenomenon to ensure the overall structural integrity; Secondly, the pins of the connector must be intact without any signs of bending, breaking or oxidation, and the insertion and extraction resistance must meet the original factory standards to ensure the stability of the connection. Thirdly, the insulation layer must be intact and undamaged. The heat shrink tubing should contract evenly without any bubbles, cracks or peeling issues to ensure that the insulation performance meets the standards. Fourth, the label identification should be clear and distinguishable, accurately reflecting the model, specification and installation position of the wire harness, and firmly adhered without falling off, facilitating subsequent maintenance. Fifth, the entire wiring harness must be kept clean, free of oil stains, dust or other foreign substances to prevent impurities from affecting electrical performance. ​

All reworked wiring harnesses must undergo 100% full inspection and can only be released after passing the inspection. If any non-conformities are found, the rework process must be initiated immediately or the product should be scrapped. The type of quality issue, handling measures and responsible person should be recorded in detail to form a complete quality traceability system. ​

IV. Ultimate Performance Verification of the wiring Harness after Rework

Passing the appearance inspection does not mean that the rework is completed. The reliability of the wiring harness still needs to be verified through strict performance tests, among which the waterproof test and durability test are the key links. ​

The waterproof test uses a high-pressure water gun to simulate an extreme rainfall environment. The test water pressure must meet the industry standard requirements (usually no less than 8MPa), and the reworked wiring harnesses are thoroughly rinsed in all aspects. During this process, if any water seepage occurs at any point, it will be judged as a test failure, and the sealing structure needs to be re-inspected and repaired. The impact force of the high-pressure water gun is sufficient to cause a significant impact on the human body, and the wiring harness needs to remain absolutely sealed in this test, fully demonstrating the strictness of its waterproof performance requirements. ​

Durability testing is the ultimate verification of the long-term reliability of the rework bundle. During the testing process, the wiring harness needs to cycle and switch between extreme environments such as high temperature (70-85℃), low temperature (-30 to -40 ℃), humidity (relative humidity above 90%), and dryness (relative humidity below 20%), simulating various usage scenarios that the vehicle may encounter throughout its entire life cycle. The test cycle usually needs to cover the designed service life of the vehicle (generally 10 years or 200,000 kilometers) to ensure that the reworked wiring harness can still maintain stable performance during long-term use and avoid later failures caused by insufficient durability. ​

In conclusion, the rework of automotive wiring harnesses is a systematic project that integrates precision, craftsmanship and standards. Its significance lies not only in the repair of faults themselves, but also in ensuring the safety of subsequent vehicle operation through strict quality control. From core process operations to potential risk avoidance and final performance verification, each link must follow professional standards to ensure that the reworked wiring harness reaches the original factory quality level, providing a solid guarantee for the stable operation of the vehicle's electrical system.