The headlights on the car keep overheating the.

I may have addressed this in another answer.
You say you changed out the harness? As a matter of deduction, you must also have changed out the head lamps. Just because they fit in the socket may not mean they are the right ones. Please check manufacturer specs to be sure.

Heat in the lights are caused by current going across the filaments, the filaments then glow and excite the gas in the bulb. Too much current, and the bulb get hotter than normal.
Please check the voltage going to the bulbs.
Check the right bulb for the car
Check ventilation to remove the heat (if any)