My timing light is nearly as old as my Alpine, but it has two power leads, positive and negative as well as the inductive pickup. With an incandescent lamp it is not sensitive to orientation of the inductive pickup. Modern lights if using LEDs might be direction sensitive, but I’m not familiar with their circuitry. No harm done, if it doesn’t work in one direction, just turn it around. I’m sure those with more info will chime in.