If the previous owner just "amputated" the wires and removed the hardware, you could have loose wiring. If he "wrapped and insulated" or pinched wires in the process, you will see this...be sure to check the wire looms and passthru areas in the fork area and rear fender wiring areas as well. Simple DMM using voltage checks or preferrably using unpowered bike and ohmmeter (continuity/shorts) checks. Suitable DMM can be had for under $5 at Harbor Freight.