I'm a firefighter in Indiana and I bought an LED dash light for my commander. The light has a cigarette lighter plug with a switch to power it. I hate the cord being seen and would like to hardwire it to a switch I'm going to mount somewhere on the dash. How do I hardwire it to a switch? Do I just cut the cigarette plug off and run my wires? How do I know which wire from my light is positive and which is negative?