Abstract: A reciprocating piston internal combustion engine having a plurality of heads, a glow plug associated with each one of the pistons, a source of DC voltage, and a control for providing heating power to the glow plugs. The engine also has engine oil and transmission oil flowing therethrough, and a fan for cooling the oil. A first switch turns the fan on and off. There is included a central electronic control which includes thermistors for sensing a temperature related to the temperature of the engine and for providing a connection from the source of DC voltage to the glow plugs when the sensed temperature is below a predetermined value and for disconnecting the source when the sensed temperature is above the predetermined value. A duty cycle rate generator alternately connects and disconnects the source of DC voltage to the glow plugs above the preset value at a duty cycle rate which ranges from 0 to 100 percent and which depends on the voltage level of the source of DC voltage.