Primary focus on heavy truck systems including A/C, air brake systems, high pressure hydraulic systems, power train, drive line, refuse truck control and operation systems, all fire truck mechanical and electronic control systems, street sweeper control systems, computerized power train systems and electrical systems, as well as on-vehicle CNG fuel system repairs and maintenance. Diagnose and repair new on-board computer systems and sub-systems relating to electrical, fuel supply systems, and hydraulic systems, including master cylinder and proportioning valves, engine cooling systems, including radiators, heater cores and hoses, and comfort control systems, including heating and air conditioning.