One problem related to headlight switch has been reported for the 2005 Mazda Miata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 Mazda Miata based on all problems reported for the 2005 Miata.
I have had the headlight combination switch, part number nc11-66-122 fail in this Mazda Miata 6 times. After the first replacement I noticed all the subsequent failures were due to a mechanical failure in the switch and not an electrical problem causing the failure. When the switch fails, I turn it to either parking lights or headlight position and the lights will not come on unless I physically continue turning the switch past it's "on" position. Soon as I release the switch and it falls back into the "on" position, the lights go off. The first 4 replacements were performed by Mazda dealers under warranty. Of course, they do not try to figure out the cause of the failure, they merely replace it. The fifth replacement I was able to keep the defective part and I disassemble it and found the contacts were not touching unless the switch was turned past the "on". I am now in the process of having the 6th combination switch replaced. On this present failure I can also physically push the switch inward and the lights momentarily come on then turn off when I release the inward pressure. My assessment of the problem is a poorly manufactured switch. It is definitely a safety hazard should the switch fail at night. Failure date mileage serviced by 02-25-2008 13737 Mazda of longmont 05-26-2009 23744 spradley barr Mazda 01-18-2010 29206 spradley barr Mazda 06-01 2010 35084 spradley barr Mazda 10-25-2012 58656 coyote motors 03-??-2015 72300 part on order by courtesy Mazda, longmont.