I recently bought my RX-8 used and discovered a problem with the headlights. On the High Beams only the Passenger side works. I tried replacing the bulb on the drivers side and no effect. I hooked a multimeter up and I'm getting 11.73 volts. (I don't know if it has to be 12 or over). I've tried three different bulbs so my only guess is the power is not right. Oh and the fog lights are'nt working either. Any suggestions on where to start to fix this?

 

First thing I would do is swap the headlights.
This is assuming that Mazda kept the wiring harness/layout the same between the two sides.
Obviously you can't mount the headlight, but at least plug in the harness to see if the problem carries over to the other side.
This will tell you if you should start checking continuity in the wires running to the headlight of focus on the headlight itself.

For the fog lights not working, have you inspected the 15A fuse and the FOG relay?

 

You should see more than 12 volts...but at 11.73 the light should light. (Assuming the bulb is good...)

Did you measure the voltage across the contacts in the connector? Or just from the hot wire to ground? If you're seeing that 11.7 from hot to ground (not the connector), there's something wrong with the ground wire to the headlight.

Ground wires tend to be more of a problem than hot wires. The places where they connect to the chassis are not as well protected as the hot connections in the fuse box.

Ken

 

Ya, first thing I'd do is check all the fuses.

 

I've checked the bulbs and they're good, and all the fuses are good, I'll check the voltage from hot wire to ground today.

 

OK after checking it a couple of different ways here is what I get. If i disconnect the passenger side High Beam I get 11.7v to the driver side high beam, but the bulb does not light on the driver's side. If I connect the passenger side high beam that bulb lights, and then the voltage to the drivers side drops to 8.7 Volts. Sorry for not being more clear earlier.