How do car circuits run?
4 Answers
From the positive terminal of the battery, the wire runs directly to the positive terminal post of the starter, and then a thinner positive wire is extended from there to other circuits. The ignition, instrument panel, and indicator light circuits must pass through the car key to complete the circuit. Electrical devices that need to be connected regardless of whether the engine is running, such as the radio and cigarette lighter, are powered by a dedicated position on the ignition switch.
The routing of car wires is actually quite particular. From my experience, they mainly run along the internal frame of the vehicle to avoid friction or high-temperature components. The wiring typically starts from the battery, passes through the firewall under the hood, and then extends along the floor channels to various corners, such as the rear light clusters and the front dashboard. This design is intended to protect the wires from engine heat or road debris damage, with the wire harness usually wrapped in plastic sleeves to cushion vibrations. If you're modifying your car, be careful not to route wires near moving parts, as prolonged exposure can lead to wear and tear, potentially causing short circuits. I recommend checking the wiring layout manual when buying a car to understand the main routing paths. This can help you quickly locate problem areas during troubleshooting, especially around the engine compartment and trunk where wires are densely packed. Regularly inspecting the condition of the wire harness is also crucial—if you notice any cracks, address them immediately to prevent driving safety issues.
I have dealt with many automotive wiring issues, and the most common problem is improper wire routing leading to malfunctions. When designing the wiring, try to avoid sharp edges or moving parts. For example, flexible wires should be used near door hinges to prevent damage from repeated bending. From the front to the rear of the vehicle, the main wiring harness is usually hidden within the body frame and secured with tape or clips to reduce friction-related risks. If you want to inspect it yourself, start by tracing from the positive terminal of the battery and check if the branch wires connected to the headlights or air conditioning system are loose. I once encountered a situation where the wiring got damp and corroded after rain because the routing position was too low and prone to water accumulation. That's why I always remind car owners to maintain their wiring more frequently before the rainy season, as it can extend the vehicle's lifespan and prevent sudden breakdowns.
The wiring layout of a car is primarily designed for safety to prevent short circuits or fires. Designers meticulously plan the routing to keep wires away from high-temperature engine areas, running them through internal pathways in the vehicle body, connecting to critical components such as the ECU and sensors. During maintenance, care should be taken to avoid pulling or exposing the wiring harness, which can help reduce malfunctions.
