Additional Key Information:Number of Pins: 2 The most important aspect of driving is letting other road users know what your actions are. Reverse Lights are used to let other road users know that you have selected reverse gear, and are intending to travel backwards. If your Reverse Light Switch is no longer working, then this means that the Bulb will not illuminate to inform other road users. Failing this, then it can lead to an instant MOT failure.