A reply from a Toyota NZ representative: Dear Mr Doran Thank you for your enquiry to Toyota New Zealand regarding the headlight switch on your Toyota Corolla, registration XXXXXX. The Toyota Motor Corporation have carried out investigations, and it was found that the issue is caused by silicon contamination on dimmer switch contacts. This is caused by continual on/off operation of the dimmer switch which leads to build up of silicon oxidation and reduced continuity of switch contacts. Also, many automotive interior and exterior cleaning products contain silicon, as well as a number of hand creams and sunscreens. We recommend that car cleaning products containing any silicon are not used on either the interior or exterior of vehicles. As the warranty on your vehicle has now expired and due to the mileage on your vehicle, unfortunately we are unable to assist you in recovering the costs for this repair. We thank you again for contacting us and we hope this response provides you with the clarification you require. Kind Regards