Well, I have been an Rx-8 owner and forum member for a few years now and this is the first time I have needed any
help from the forum. Not bad if you ask me.

So this is the problem. A couple weeks ago my battery started getting a little sluggish and then it completly failed. I had it tested and it wouldn't hold a charge. It was a 6 month old Optima red top. This battery shouldn't have failed so upon installing a new battery I decided to test my system to see if something was draining it. Sure enough it was pulling 8 amps with everything off. I isolated it to a 30 amp fuse labelled BTN. The draw goes to zero when this fuse is pulled, but I don't know where to go from here. I pulled all the relays in the fuse box but that didn't stop the draw, so there isn't a bad relay. It must be a short or failed part somewhere within this system but I don't know how to check for that. I don't know what. BTN means but with this fuse out my power locks don't work as well as the radio, interior lights, windows, power seats, and who knows what else. That is all I could find for now. I would appreciate any help you guys can offer. I can't really afford to pay Mazda to fix this.

The car is a 2006 GT fully loaded completely stock with 40,000 miles.

 

Your location saids GA, OD will come in soon and point you to the right direction

OD, WHERE ARE YOU ! SHOW YOURSELF!

btw, electrical stuff is a bitch to fix. You can look at the FSM's electrial graph and see where is it going.

 

BTN supplies all the interior and exterior lights....

One of the common failures on that system is the drivers side lighted sunshade, is yours cracked and shorting out maybe?

 

None of the above. turns out it was a case of stupidity. I started checking fuses in the kick panel but realized with the door open it would draw a lot of amps trying to turn the interior lights on. I went inside and started to manually turn them off. That's when I noticed one of the small side lights was pressed on. The little light next to the main light was draining the battery. Don't tell optima the failed battery was my fault. I haven't pulled a bone head move like this in a while. Thanks for the help though. I'm now open to jokes and ridicule. let it fly!

 

One time, the back of my car was open, but not all the way open, and I realize why my battery was draining fast. I just bought the battery a year ago, and it shouldn't be draining that fast. So, I thought that the battery was kinda defective or something. And I found out that the back of my car was opened accidentally by pushing the remote. Never knew I accidentally pushed the button to open the back.

 

Hey, I had a brand new battery, and left for 3 months knowing that I had done it before, and it started.

However, this time the battery is dead. After getting new one again, I notice one of the map lights is on. WTF!?

I thought I left it when dark so I could see lights off.

I'm pretty sure that I heard the horn chirp when I locked it up. I thought if you could honk, everything is turned off. Is that wrong?

 

Not for the interior lights, or any lights! The horn for alarming the car will only do it if your doors are closed. If the trunk and/or the hood are open, it will still honk to confirm that they are locked; however, the hazard lights will not flash until the hood and/or trunk are properly closed.

 

2004 RX 8, battery drains all the way down. Take it to the Mazda dealer near my home in Florida. Battery won't hold a charge, gets replaced. Mazda guys can't find a source for battery drain. Exact same thing happens 2 more times in the next year. Have to buy new batteries and the problem keeps occurring.

Move to Georgia and happen to find a shop where they do automotive electrical work. The guy keeps my car overnight and finds the battery had been getting drained overnight. The best he could do to locate the source was to remove one fuse at a time until the drain went away. Said it was in the electrical components served by fuse 4, aka BTN, a 30 amp that serves power windows, power door locks, illuminated entry system, sunroof. Tells me that he can go no furthter, I'll have to go to a Mazda dealer.

I get into the habit of removing fuse 4 any time I'm not driving the car and the battery drain problem goes away.

Then I go to a Mazda dealer in Georgia who keeps the car overnight, calls me the next morning with the "good news" that they found no battery drain.

I'm still removing the BTN fuse whenever I'm not driving the car and I've had no further battery drains.

I'd like to sell this very nice but gas-guzzling car but don't want to put a defective car on the market with a problem no Mazda dealer I've gone to can figure out.

 

I been having this same issue with the btn fuse. I can't figure out what it might be. I need help please.

 

Check short in sunvisors - very common on RX8. Could also check trunk light, not so common with Rx8 but very common P.Drain issue...

 

Thank you, thank you, thank you!!!! This is exactly what the problem was only it was the passenger side. I have a '93 Escort which I think is a Mazda design. With the 'flap' closed over the light/mirror I had no way of knowing it was on and I rarely drive at night.