Truck circuit failures are more than wear and tear

When it comes to vehicle wiring harnesses, it is indeed something that many truck owners have to pay attention to. Minor problems can cause speed and torque restrictions, while serious issues can lead to vehicle fires.

In order to accurately diagnose faults, we first need to understand several maintenance and repair methods. However, the most important thing to pay attention to during repairs is personal safety as well as the safety of the vehicle's electrical components. Therefore, before disconnecting power, the ignition switch should be turned off, and electrical equipment such as audio devices should be turned off. It is prohibited to suddenly cut off power while electrical equipment is running.

power failure sequence

From a safety point of view, the maintenance should first pull out the negative terminal, and then pull out the positive terminal to install just the opposite, first install the positive terminal, and then install the negative terminal.

Why should the negative pole be disconnected first?

Removing the positive terminal first truckries the risk of damaging electrical components and may cause the computer board to burn out. In practice, many people have damaged circuits and burned their hands due to violating operating procedures. This is because the short-circuit current between the positive and negative terminals of the battery is very large, generating high temperatures in an instant.

If the positive pole is unplugged first, since the negative pole is grounded, that is, the metal truck body around the positive pole is the negative pole. If the tool touches the nearby metal truck body when disassembling the positive pole connection, it will cause a short circuit between the positive and negative poles of the battery.

If you disconnect the negative terminal first, since the metal truck body around the negative terminal is connected to it, it won't result in any adverse effects even if the tool touches it. Once the negative terminal is disconnected, the power is cut off, and it becomes safe to disconnect the positive terminal.

Although there are various forms of power switches on trucks, during repair operations, especially when welding the vehicle body, it is still necessary to disconnect the battery according to the repair operation procedures to avoid damage to the vehicle's electrical equipment. Common faults in truck circuits include: open circuit, short circuit, damage to electrical equipment, etc. However, ultimately, most of these faults are caused by the aging of the wiring harness.

The causes of wire aging are usually due to prolonged use, resulting in the breakdown of the outer insulation layer. However, the aging of the wiring harness on trucks cannot be interpreted literally. We need to look at it in two parts:

The first is a very common reason. The wiring harness is made up of multiple strands of copper wire with a plastic outer skin. The temperature near the engine is very high, and the plastic inevitably releases chemical substances such as plasticizers. These chemicals react with the copper core wire. It's like the black substance produced when we ignite plastic with a lighter. This will reduce the strength of the plastic and increase the resistance of the copper core inside, leading to vehicle fault alerts.

The second cause of aging is physical. This is easier to understand. It's the common wear and tear from bumps and knocks. The wiring harness in trucks will be severely jolted during driving, and many of the routing paths of the truck's wiring harness are also unreasonable, making it easy to wear and break. This is usually also considered within the scope of aging.

The main reasons for wire harness aging and their corresponding solutions are as follows:

Long-term overloading or overloading operation: When the vehicle is starting, running the air conditioner, and other high-power operating modes, the wire harness is in high-load operation. Therefore, when we are learning to drive in a driving school, coaches will severely scold those who continuously stop and start the engine. The same is true for trucks. Long-time operation can cause the wire conductor to heat up, thereby accelerating the aging process. The solution is to avoid long-term ignition requests.

Environmental and Temperature Factors: The external environment and heat sources where the wiring harness is located can cause excessive temperature, insulation breakdown, and even fire.

Physical Damage: Many vehicle faults are actually caused by physical wear and tear, leading to wire exposure and short-circuiting, which then triggers a vehicle fault report.

Route the wiring correctly, add abrasion-resistant shields to the wiring harness at easily worn locations, choose matching wire numbers and holes, and bundle them together. Also, add protective sleeve structures between the connectors and the external corrugated tubes to avoid wire exposure.

Wire harness connector failure is a common problem in cable circuits, and connectors are the weakest link in the cable system, often caused by human error. This requires personnel training on the installation.

Chemical corrosion is also a common problem, including battery leakage corrosion, urea corrosion, and severe corrosion of vehicle wiring harnesses due to external leakage during rainy weather in many southern regions, resulting in the failure of the protective layer and reduced insulation, which can also cause false vehicle faults.

Indeed, this requires truck owners to pay attention and regularly check and clean the vehicle's external wiring harnesses, as well as inspect for leaks in the vehicle's radiator and urea tank to prevent chemical corrosion.