Symptoms of a Bad Ignition Switch

A hand turning a key in a car's ignition switch.

If your vehicle is having trouble starting, it could be showing signs of a failing ignition switch. Some symptoms may be similar to other problems like starter motor issues. If your ignition switch is showing signs of malfunction, you will notice a wide variety difficulties which need to be investigated to find the underlying problem.

Check the Status of the Switch

Normally, when you put the key in the ignition switch and turn it, you will have three positions of ignition status. The ‘off’ status means that no power is being transmitted to the engine or system. The second position is the ‘on’ position where the dashboard lights come on but your engine will still be off. The third position is the ‘start’ mode where you exert key pressure to actually fire the engine up. One major sign of a bad ignition switch is that the instrument panel will not light up when the key hits the second position.

Problems Starting and Running Your Vehicle

What should happen when you start up your vehicle is the ignition coil will take its power from the battery and relay it to the spark plugs. This ignites the fuel and makes your vehicle run. A major symptom of a recognizably problematic switch is if the vehicle is fails to start. If you have to turn the engine over a few times to attempt ignition, you could also drain your battery until it has no power to start the vehicle. Your vehicle can also be prone to stalling when you run it on idle.

Overheating Switch

Another symptom of a bad ignition switch is if it is overly hot when touched. This is an accurate sign that the ignition switch problem could be rooted in the electrical system. The ignition switch is connected to a series of high-resistance wires and any of the terminals connecting these wires can overheat. This causes an arcing of the terminals which can melt the insulating base. When this occurs, the vehicle will jerk quite violently and will not start despite repeated efforts.

Watch Your Dashboard Lights

In older cars, the natural wear and tear on a vehicle can lead to ignition switch failure. If the switch is failing, you will probably not hear any clicks from the main relay, which fires the ignition. Check the behavior of the dashboard lights if your vehicle stalls as mentioned before. Alternatively, when the key is first turned to position two, the oil light, brake light, charge light, and other warning lights will not function. You can try a test to check the integrity of the ignition switch by turning the ignition key to the ‘start’ position. As soon as it tries to start, let go of the key. Allow it to snap back to the ‘run’ position and note warning lights. If they go out as the switch snaps back then the switch is faulty.

If you find that your ignition switch is faulty due to electrical issues and wiring, you may have a short in your system. Be careful when handling electrical wires if you're replacing your own ignition switch because there is a current running through them that can cause you bodily harm, so keep metallic objects away from electrical wires. Disconnect battery at ground terminal to assure the wires are safe to handle.