There are three common forms of fatal faults in terminal blocks:
1. Poor contact
The metal conductor inside the electrical terminal of the automobile wiring harness is the core part of the terminal, which transmits the voltage, current or signal from the external wire or cable to the corresponding contact of the matching connector. Therefore, the contact piece has an excellent structure, stable contact retention force and good electrical conductivity. Due to the unreasonable structural design of the contact parts, the wrong selection of materials, the unstable mold, the excessive processing size, the rough surface, the unreasonable surface treatment process such as heat treatment and electroplating, improper assembly, poor storage and use environment and improper operation and use, the contact parts will be damaged. Contact parts and mating parts cause poor contact.

2. Poor insulation
The function of the insulator is to keep the contacts in the correct position, and to insulate the contacts from each other, and between the contacts and the housing. Therefore, the insulating parts have excellent electrical properties, mechanical properties and process forming properties. Especially with the widespread use of high-density, miniaturized terminals, the wall thickness of the insulator is getting thinner and thinner. This puts forward more stringent requirements for insulation materials, injection mold precision and molding process. Due to the presence of metal excess on the surface or inside of the insulator, surface dust, flux and other contamination and moisture, material precipitates and gas adsorption film and surface water film fusion to form ionic conductive channels, moisture absorption, mold growth, insulation material aging and other reasons, will cause Short circuit, leakage, breakdown, low insulation resistance and other poor insulation phenomena.
3. Poor fixation
The insulator not only plays the role of insulation, but also provides centering and protection for the protruding contacts, and also has the functions of installation and positioning, locking and fixing on the equipment. Poor fixation, the light one will affect the contact and cause instant power failure, and the serious one is the disintegration of the product. Disintegration refers to the abnormal separation between the plug and the socket, the pin and the jack, which are not caused by the structure due to the material, design, process, etc., when the terminal is in the inserted state, which will cause the power transmission and signal of the control system. Control the serious consequences of disruption. Due to poor design, wrong material selection, improper selection of molding process, poor quality of heat treatment, mold, assembly, welding and other processes, and improper assembly, etc., will cause poor fixation.

In addition, the appearance is poor due to peeling, corrosion, bruising, plastic shell flashing, cracking, rough processing of contact parts, deformation, etc., due to excessive positioning and locking matching size, poor consistency of processing quality, and excessive total separation force. Poor exchange caused by major reasons is also a common disease and frequently-occurring disease. These kinds of faults can generally be found and eliminated in time during inspection and use.