A possible cause is shorting of the power supply. See below:


One solution to intermittent or permanent headlight failure can be found on the post by SEVARGMT on 9-29-2010.

It seems to lie in corrosion of the wiring system connectors in the PJB, a specific wire connection junction box located under the passenger side glove compartment box.

It seems possible to repair the corroded pin connector but it is probably best to have the dealer replace the entire PJB to avoid repeats of this problem, as it is a dangerous situation when headlights go out at night, like mine did.

Brilliant problem solving by SEVARGMT and DJS2571. They also developed a convincing theory of what causes this problem: the air conditioning line located above this box creates condensation, which then drips down on the wire connectors and causes them to corrode, causing an electrical fault. They suggest a plastic drip sheet to avoid future corrosion.

Wouldn't it be great if Mazda assigned an engineer to read the forums for problems with their cars and prepare posts with solutions? It is plainly obvious that a problem is very common when you look at the number of "views" listed for certain topics, such the headlights (many thousands of owners have headlight failure problems). Mazda should have issued a bulletin or a recall since the corroding PJB is clearly a safety problem. This looks like a design/engineering flaw. Every electrician and plumber knows to never put moisture sources above electrical boxes. Shame on them.