DTC C1503 ESC Switch Error: General Description
WARNING: This page is about a different car, the 2007 Kia Optima, 2007 Kia Magentis, 2006 Kia Optima, and 2006 Kia Magentis. However, it is still accessible from the selected car via links, so may be relevant.
Driver can inhibit the ESC control by ESC switch. When switch signal send into HECU, ESC warning lamp goes ON and ESC control is stopped and if next switch signal is inputted again, ESC control is ready. This function is used for sporty driving or vehicle inspection.