I recently purchased an 05 RX8 with 33,000 miles. I have several problems.

1. The brake lights do not work. New bulbs and new brake switch. Fuses OK. Any ideas? All other lights work. Flashers do not.

2. The radio and AC do not work. Seems like there is no power. Fuses OK. Ideas?

We are located in Memphis. Thanks in advance for any help.

KB

 

My first gut reaction is that you have a flood damaged car, and there are corroded / damaged wires in the wiring harness.

The simple answer is that to light a bulb, you need a current generated, travels through wires to the bulb, then return to the chassis via a ground, back to the battery and cycle repeats. Bulb doesn't light, you have an issue in one of these.

1: Alternator obviously works
2: Battery obviously works
3: Fuses are ok
4: bulb is new
5: switch is new
6: only thing left is the wiring.

Either a ground problem or the wires themselves. Multiple issues suggest a single ground point in common (or two, one in common with each group), or a problem with the wiring harness. Most harness problems are self inflicted by owners (or prior owners in this case), though having owned a flood damaged car before with a silt-packed-and-corroded harness, it's a possibility too.

 

I would look under the dash to see if some wires are compromised, since you have 2 electrical problems in the same general area I would look there first....

check the wiring from the pedal switch to see if there is a completed circuit.....follow it through the harness till you find the problem.

 

Both curcuits in question are +12V Switched-Ignition. I'd start by checking the ignition switch and going from there.

Never had one fail on any Mazda I've owned, but it's very common in the VW world. Bosch makes their ignition switches...replaced more than a couple in my days with german cars. Who makes the ones for the RX-8?

-Adam

 

1.) The brake lights are not switched ignition, as they can be lit up without the key. I haven't looked at an RX-8 wiring diagram specifically, but often, the brake like wiring goes through the combination (turn signal/headlight) switch. And I am almost certain the flasher circuit goes through the combination switch.

2.) Have you checked the "BTN" 30A fuse under the hood? That circuit goes to the radio. But what specifically do you mean by "the A/C doesn't work"? Is it the fan that doesn't work, or the A/C clutch doesn't engage, or it just doesn't get cold, or some other symptom?

I wouldn't presume that all symptoms are from the same root cause... At least not yet.