For this problem, 1. First, connect the power cord of the welcome light to the power cord of the vehicle.
2. Then, connect the negative wire of the welcome light to the ground wire of the vehicle.
3. Finally, add a switch to the circuit, connect the positive line of the switch to the positive line of the welcome light, and connect the negative line of the switch to the ground line of the vehicle.
It should be noted that when connecting the wires, it should be ensured that the wires are tightly connected and will not loose or cause short circuit. At the same time, appropriate wire specifications and insulation materials should be selected to ensure the safety and reliability of the circuit. If you are unfamiliar with circuit connections, seek professional help.