Abstract: A control system is disclosed for turning a diesel engine on and off to power a refrigeration plant, based on temperature requirements. The desired temperature limits are preset, and when these limits are exceeded, a first timer is set for a desired delay, during which the engine is off; delay times of up to one hour are usual. At the end of this delay time, the first timer will activate glow plugs in the engine. Simultaneously with turning on the glow plugs, a second timer actuates the engine starter after a short delay to start the engine. During the delay period set by the first timer, the diesel engine will be off, and hence, the control system saves diesel fuel and reduces engine maintenance. An electronic circuit for operating the timing system is also disclosed.