An ignition switch has several purposes, but its main function is to initiate power to a vehicle. It connects the starter to the battery, allowing the transmission of electricity between these parts. If the ignition switch malfunctions, electricity is not properly transmitted through the ignition system and various symptoms may develop.
Since the ignition switch is essential for vehicle power, the most common indication of a faulty switch is a vehicle that has power problems. The engine will not turn over when the ignition switch is turned. The engine may start when you hold the key in the correct position, but when the key is released, the car loses power again. Also, the vehicle may suddenly lose power while in idle.
An ignition switch may become overheated if it is damaged. The switch may become extremely hot, preventing you from touching it. This happens when an electrical circuit within the switch malfunctions. If the ignition switch overheats, it will not turn to initiate power to the vehicle. In some cases, the switch may become hot enough to spark a fire. In 1996, Ford Motor company recalled over 8 million vehicles due to fire hazards caused by faulty ignition switches, according to the Crashworthiness website.
Sometimes a vehicle that will not start indicates a battery problem; however, working interior and exterior lights when there is no power will often signal an ignition problem. If the headlights and dashboard lights are working but the vehicle still does not start, the ignition switch is most likely the problem. In contrast, if the oil, charge or brake lights are not visible when the ignition switch is turned into the start position, the switch may be faulty. Also, the dashboard lights may turn off when the vehicle loses power, but the speedometer and tachometer lights will come back on again.