I used some small speaker wire for light, 2mm female crimp lug and flattend bootlace lug. wire to battery negative connection, make up small male and female plug as pictured on end of positive connection to light. remove single wire plug from compressor, and Plug female end onto compressor and male end into plug removed from compressor. light will be on when sysrem is calling for cooling, if this light comes on ang ac is warm stop pull over and pop the bonnet abd see if the compressor is turning