Contact resistance is the core indicator of wire harness quality, and control needs to start from multiple aspects. Firstly, the crimping process between terminals and wires is crucial, ensuring that the crimping height and compression ratio comply with specifications to avoid insufficient crimping (resulting in a small contact surface) or excessive crimping (damaging the conductor). Secondly, surface treatment of terminals affects conductivity, and processes such as tin plating and silver plating should be used to reduce the oxide layer and control the uniformity of coating thickness. In addition, the wire material needs to match the terminal, such as copper conductors with tin plated terminals, and aluminum conductors that require ultrasonic welding or specialized connectors. The detection process cannot be ignored, and it is necessary to measure the contact resistance through a micro ohmmeter and simulate environmental factors such as vibration and temperature shock to verify long-term stability. Finally, avoid excessive bending or stretching during wire harness assembly to prevent conductor breakage or loose contact points. Through process standardization, material matching, and strict testing, contact resistance can be effectively controlled, and the conductivity and safety of wire harnesses can be improved.