Ignition Switch On (Engine Off)
WARNING: This page is about a different car, the 2016 Jeep Wrangler and 2015 Jeep Wrangler. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition is turned on, the PCM activates the glow plug relay for a time period that is determined by engine coolant temperature, atmospheric temperature and battery voltage.