TM 9-2320-361-20 1-20. ELECTRICAL SYSTEMS OPERATION (Contd) e. Gage and Warning System Operation. OIL PRESSURE GAGE - Indicates pressure of oil circulating through vehicle engine. Receives electrical current from oil pressure sending unit located on engine block. ENGINE TEMPERATURE GAGE - Indicates temperature of engine coolant circulating through engine. Receives electrical current from engine temperature sending unit located on engine block. WARNING BUZZER - Produces a loud sound to warn vehicle operator that the low air pressure switch has been activated. LOW AIR PRESSURE SWITCH - Activates warning buzzer to sound when pressure in compressed air system is not high enough to safely operate vehicle. BATTERY/GENERATOR GAGE - Indicates amount of voltage in electrical system provided by batteries and alternator. FUEL GAGE - Indicates amount of fuel in fuel tank. Receives electrical current from fuel tank sending unit located in fuel tank. 1-59