Function

The battery voltage is switched on or off with the ignition switch, which is located at the end of the ignition lock.

As the lock cylinder is rotated within a fixed housing with the key, the switch operates in four positions: off, accessories, ignition/on and start.

In the accessories position the non-engine related electrical circuits, are enabled, for example; radio, power windows and lights.

In the ignition on position, this supplies the various control units with battery voltage.

The start position engages the starter motor and when the key is released it returns to the ignition/on position when the vehicle is running.

Cause of failure

Over time, the contacts within the switch can wear resulting in a poor contact or high resistance.

An early sign of the ignition switch starting to wear is having to apply some inward pressure or oscillating the key when starting the vehicle.

Other symptoms include intermittent non-starting, vehicle stalling and poor engine performance and a discharged battery.