Method for connecting a glow plug for operation at two different voltages

摘要

A method for providing uniform thermal output from a glow plug for use in an auxiliary heater of a motor vehicle having either a 12 volt or 24 volt power supply without the use of multiplier resistors utilizes a glow plug having two heating rods having the same electrical resistance and three electrical terminals. One end of the first and second rods are permanently electrically connected respectively to the first and third terminals and the other end of the first and second rods are permanently electrically connected to the second terminal. The vehicle voltage is determined and if the 12 volt supply is present the first and second terminals are connected to the power supply and the first and third terminals are electrically connected to each other to place the heating rods in parallel. If a 24 volt supply is present, the first and third terminals are connected to the power supply with the second terminal left in connected thereby placing the heating rods in series.