The conductivity of plastic insulation materials and automobile terminal is the key factor affecting the quality of automobile terminals. They determine the insulation and conductivity of automobile terminals respectively. The failure of any connection end will lead to the failure of the entire system engineering. Needless to say, there are many warning cases. As a precision operation accessory, the quality of motion control terminal has always been a concern of users. How to effectively detect and prevent has become a topic of concern.


Common failures of automobile terminals

From the perspective of use, the function of automobile terminal is: the contact point shall be connected, the contact point must be energized and the contact shall be reliable. The insulation must be reliable. There are three common fatal faults at line terminals

1. Poor exposure.

The metal conductor within the terminal is a core component. It transmits voltage, current or signals from the external wire or cable to the corresponding contact, which is the connector. Therefore, the contact point must have excellent structure, stable and reliable contact retention force and good electrical conductivity. Unreasonable contactor structure design, improper selection of materials, poor die stability, out of tolerance processing size, rough surface, unreasonable heat treatment coating and other surface treatment processes, poor storage and use environment and improper operation will lead to poor contact between contact parts and coordination parts

2. Poor thermal insulation performance.

The function of insulator is to keep the contact in the correct position and insulate between contact and contact, contact and shell. Therefore, the insulator must have good electrical, mechanical and process forming performance. Especially, due to the wide application of high density and small size connectors, the effective wall thickness of insulator is also getting thinner and thinner. More stringent requirements are put forward for insulation materials, injection mold accuracy and molding process. Because there are metal residues, surface dust, welder agent and other pollution on the surface or inside of the insulator, the precipitation of organic matter and the fusion of harmful gas adsorption film and surface water film form ion conduction channel, moisture absorption, mildew, insulation material aging, etc., which may cause short circuit, power leakage, breakdown, low insulation resistance and poor insulation.

3. No-fixed-position issue

The thermal insulation material not only provides insulation effects, but also usually provides accurate neutralization protection for extended contacts. At the same time, it also has the function of installing positioning and locking devices.

If the installation is not good, it will affect the contact and cause instantaneous power failure, and the product will disintegrate in serious cases. Disassembly refers to abnormal separation between plug and jack, due to unreliable structure caused by materials, design, process etc when the connector is plugged in, which will seriously affect the power transmission and signal control interruption of the control system. Poor installation is caused by unreliable design, improper selection of materials, improper selection of forming process, poor process quality such as heat treatment, mold, assembly and welding, and inadequate assembly.

In addition, poor appearance caused by coating peeling, corrosion, collision, plastic shell flash, fracture, rough processing and deformation of contact parts, and poor shaping caused by poor positioning size, poor processing quality, excessive total separation force etc. These faults can generally be found and eliminated in time during inspection and use.

How to check the terminal short circuit fault?

Failure of lead and terminal may also be caused by a short circuit between the harness and the body (ground wire) or within the relevant switch. First check whether the automobile terminal is firm, and then carry out the test according to the following steps

1. Check the connection of the wires.

First remove the control terminals on both sides of the control computer ECU and the sensor, and then measure the resistance between the corresponding terminals. If the resistance does not exceed 1 ohm, the power line is normal for the next inspection. When testing the conductor resistance, it is best to gently shake the conductor in the vertical and horizontal directions to improve the measurement accuracy. Multiple wire terminals shall be inserted with multi-meter bars from the back end of the connector. However, the waterproof automobile terminal rod cannot be inserted from the rear end, because the terminal will be deformed if it is accidentally inserted.

2. Detect the short-circuit resistance value

First disassemble the ECU of the control computer and the wires automobile terminals on both sides of the sensor, and then measure the resistance value between the connectors and the body. During the measurement, one end of the meter bar is connected with the iron body, and the other end shall be measured respectively on the two wire connectors. If the resistance value is greater than 1Ω, it indicates that there is no short circuit fault.

3. Terminal appearance and contact pressure inspection.

First disassemble each terminal one by one and check whether there is rust and dirt on the automobile terminal. Then check whether the junction box is loose and damaged, whether the junction box is firm. Make sure the junction box is not loose after light pulling. Conversely, if it is easier to pull out the plug end, the socket may cause failure with poor contact during use.