The role of the door harness protection sleeve is to protect the wire. The power supply and various electrical parts on the car through the wiring harness to achieve the physical connection of the circuit. The wiring harness is all over the car, the car door system is an important collection of functional parts, the requirements for its wiring harness system are high, the door harness system is also one of the more complex wiring harness systems on the car, especially pay attention to the arrangement of wiring harnesses.