Flash for pass was the only headlights working

A local technician I know had a problem with head lights only working in the “flash for pass” position on a 2003 Mazda 6. There were no running lights, no low beam or high beams. This was puzzling, at least the high beam bulbs were good and it wasn’t really possible for all the exterior lights to have bad bulbs. After checking all the usual things like the fuses in the passenger compartment fuse panel and the one under the hood and switching a few of the relays to see if anything would happen… nothing. The high beam indicator on the dash DID light up indicating that the switch was doing something and the switch felt normal; sometimes on cars if a switch feels funny, loose or worn that would be an indication of a problem.

Mazda 6 headlight module located to the right of steering column

Even after checking Google for free auto repair information like in Mazda forums that may have posted a similar problem… NOTHING. The next step was to check for TSB’s (Technical Service Bulletins) and to find a wiring diagram of the headlights and other exterior lights. Being a professional technician the shop provided access to Mitchell 1 so access to repair info. wasn’t a problem. There were no TSB’s related to headlights found. The wiring diagram printed from the Mitchell1 repair manual software, showed several things. What it revealed was, there is a control module for the headlights located under the dash beside the steering column.

The first thing that stuck out when looking at the wiring diagram was that the flash for pass does not go through a module like the rest of the exterior lights on this model. Remember the flash for pass was the only exterior lights working so this makes the module the most likely cause of the problem. After turning the headlight switch to the low beam “on” position, probing and checking the wire coming out of the module that was suppose to power the low beams – no power was found. Powering this wire up with a Power Probe, the headlights worked! This verified that everything downstream from the module like the relays and wiring was working. After replacing the module everything was working again… headlights running lights and all. Without the wiring diagram this would have taken a lot longer to diagnose. This was a 2003 Mazda 6 – other years or models may have an entirely different system, finding the specific auto repair manual info can make all the difference in the world. See our car repair manual page for access to specific diagrams and info. for your vehicle.