Trombetta-Tympanium’s S500-B100 Series Diesel Pre-Heat Module is a temperature-dependent preheat module that provides optimum control of diesel engine glow plugs and air intake heating elements. When the ignition switch is turned to the run position, the module powers the glow plugs and/or air intake heating elements. This keeps them energized for a predetermined time (from 3 to 30 s) based on the ambient temperature. Simultaneously, the module can activate a dashboard “wait” indicator light, which remains on until the glow plug or air intake heater reaches the required temperature and then turns off, signaling the operator to turn the key to start the engine. The unit is rated for a 40-A resistive load and a voltage range of 6-18 V dc. Additionally, it provides transient protection up to 30 V to safeguard the module from damaging voltage spikes within the engine compartment.