Causes and maintenance of grounding wire failure

The fault of the grounding wire can be roughly divided into two categories: open circuit fault and short circuit fault. These two faults have different maintenance methods. The following Jiangsu wire harness factory will introduce you in detail:

1. Open circuit failure

Depending on the maintenance work, there are two cases depending on the flow state of the current: a complete disconnection and a non-smooth fault.

(1) Complete open circuit: Under normal circumstances, the wire is broken and the terminal is rusted. This failure has lost its role in the ground line. In severe cases, the appliance may not work or the work is obviously poor. Under normal circumstances, the fault can be detected by visual inspection. If the fault cannot be found by visual inspection, resistance measurements, electronically controlled detectors or other auxiliary devices can be used to determine the exact location of the fault point.

(2) Poor conduction: mainly due to wire breakage, corrosion of wire terminals, loose connection terminals, and poor basic components. Many automotive circuits are digital signals and high precision analog signal circuits. If there is a bad contact fault on the ground line, it is equivalent to connecting a resistor in series with the circuit, which may cause high-precision signal misalignment, so only good wires can meet the requirements. Typically, the point of failure can be found by visual inspection or by testing a resistance check.

2. Short circuit fault

(1) The line feed terminal is short-circuited. The line feed end refers to the power line in front of the appliance, such as the motor, the lamp and the electromagnetic coil. A short circuit at the wire feed end is usually caused by damage to the wire layer. The reason for the wire insulation damage is that when installing some body parts, the fixing bolts are tightened too tight, the wires are too loose, the liquid enters the insulation layer, and the insulation layer is too close to the engine hot parts (such as the exhaust manifold). Most of the damaged parts can be seen if they are burned or damaged by the sharp parts of the body metal or rubbed against the body parts. However, not all damaged parts can be visually inspected directly, as some parts may be hidden inside or inside the door. For such faults, simply follow the steps and exclude them according to the circuit diagram and line direction.

(2) The line is shorted to the ground. Ground the line and use the line after using the equipment. Since many electrical terminals are controlled by switches, the diagnosis of short-circuit faults at the line ground is cumbersome. If the short-circuit point is before a manual switch or other control switch, or even if the switch itself is short-circuited, the drive will not be able to disconnect the device. When the appliance cannot be disconnected, the diagnosis is usually started from the appliance. First disconnect the electrical ground of the appliance. If the line is disconnected (if the light is off or the motor is not working), the problem is at the ground of the line, then the circuit diagram. Check the circuit of each connection point. For the switch at the end of the grounding, you can use the test pen to check for a short circuit. If the switch is still conducting in the off position, the switch is shorted and should be replaced. Since the circuit conductor is relatively long, it cannot be searched from start to finish, so the efficiency is too low. Find the most likely breakpoint or short-circuit point according to the characteristics of the line wiring; first check the parts that frequently vibrate at high temperatures (such as the tortuous part near the engine and the exhaust pipe, the line brake normal wear warning on the steering wheel and the ABS line, and often Switching parts, such as trunk harnesses, can often find problems at a critical juncture.