The thin red wire is connected to the "+" port of the battery, and the thin black wire is connected to the "-" port of the battery. Switch can work with power then;
Two large terminals on the electromagnetic Valve are the main switch, one in ,the other out .(They control "-" or "+" port of the battery actually);
If you want to control the "-" port, one large terminal is connected to the "-" port of the battery in, the other large terminal is connected to the "-" port of the battery out.
Normally we control the "-" port of the battery; 4. If you want to control the "+" port of the battery, one large terminal is connected to the "+" port of the battery, and the other one is connected to your car; 5. To prevent battery short circuit during installation, Pls ask the special car shop for help if you don't know how to do it.