2008 Gem car e4 battery indicator not working and can't change from mph to kph

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I have 2008 Gem car e4 that I just replaced the motor. I installed a speed calibrator and to set it properly the directions say to change from mph to kph. It has a switch on the right hand side of the steering wheel thats supposed to change this mode by holding the switch down for a few seconds. I tried this and nothing changes. I removed the trim from around the switch to access the back of it so I could check for loose wires. The switch has only one wire going to it. Shouldn’t another wire go to this switch and if so what color would it be or where would it be located. I just bought this car and do not know anything about gem cars . I’m pretty mechanical inclined and can normally figure things out pretty easy but I don’t want to short out a brand new motor by hooking up a wrong wire. I’m probably gonna be blowing this site up with questions but that’s the only way I can lean and I appreciate all of the help i can get. Awesome sight and a lot of good information… Thanks…