With the ignition turned on where required check the operation of all exterior lights. Verify the brake lights using an assistant or reversing, up close to the reflective door, make sure that all the rear lights are independent of one another, i.e., with as many rear lights as possible switched on, test your brake lights. Any unusual results are usually a symptom of an earth fault or poor connection at the rear light unit. Also, with help or using a reflective surface, make sure that the headlights are working on both main and dipped beam. Check the operation of all interior lights including glovebox and luggage area lights and that all appropriate warning lights are lit as expected when the ignition is switched on, details to be found in the vehicle handbook. After starting the engine, make sure to check that the correct lights go out. When driving at night, check to see if all of the instrument panel and facia lighting is operating properly. If there are any problems, fix them accordingly; Lastly, choose the right time of the day to test the horn's operation.