I have an 04 Mazda 3 sedan. It's a plain Jane car, no nothing, except it is an automatic.

There is a draw of 0.45 amps that keeps draining the battery. When the 'Room' fuse is pulled, the draw drops to 0.14 amps, which in my opinion is still too much, but more on that later.

I checked all the fuses under the glove box and there was no change with any of the fuses. I have pulled the dash apart, unplugging everything I can, except the cluster and I haven't found the culprit. There isn't any trunk light or door lights and I pulled the dome light with no luck. There is a kill switch that has to be activated to start the car, but this is not on the 'Room' fuse.

No air, power locks, power windows, etc. Where can the draw be from? What else is controlled by the 'Room' fuse? Any ideas as to what the next step should be?

Many Thanks,
Ian

 

As far as I'm aware, the room fuse only runs central locking & door ajar/interior lights. Will try & read the wiring diagrams tomorrow.

 

Thanks grim, (can I call you grim?), I'll be waiting with bated breath.

Ian

 

After having a browse thru the Wiring diagrams, it appears to relate to the following,

Central locking,
Door lock actuators,
Audio unit ( stereo)
Instrument cluster,
Reading lights,
Interior lights,
Boot/trunk lights,
Glovebox light,
Ash tray light,
Dash lights/ panel illumination,
Ignition switch illumination,


It looks like all of the above items/circuits have the power from the "ROOM FUSE" go thru the PJB ( Passenger Junction BOX ) also called( Microprocessor) & also known as the passenger side fusebox.

Hope this helps.

 

Thanks Grim,
I went through the fuse box under the glove box and there weren't any fuses that changed the draw on the ammeter. The only thing I haven't disconnected is the cluster, I guess that is my next move.

If that doesn't work, I guess I have to pay an auto electrician to find it.

Ian

 

These being computer controlled cars with a memory, there will be some constant draw on the system. Even the radio requires memory to retain its settings. And that it is an automatic, there is a second ECU (Electronic Control Unit) that piggybacks the main computer (ECU.) That may cause an additional draw on the system even when parked or static, but I am not familiar enough with it so that only a guess.
You mentioned removing the room light, but not the map lights. Are they set to come on with the doors? Are you testing the current draw with doors open or closed? I am assuming you know enough not the test draw with the ignition on or the (electronic) key in it....
With all that said, 0.45 amp doesn't sound like all that much to me. And 0.14 certainly isn't. What is the condition of your battery?

 

The bulb in the truck was burnt out and in the location of the light, I didn't see it before. Anyway, that light was the culprit. I pulled the (burnt) bulb and the draw went from 0.50/0.45 down to 0.14. I also replaced the battery, so now everything works fine.

Thanks for all the help,
Ian

 

I frankly do not understand that; if the bulb were burned out there would be an incomplete circuit and it would therefore not be drawing any power. If the filament within the bulb had shorted, it should have blown a fuse?
Well, whatever, I guess. As long as it's working properly now.... Did you or will you replace the bulb with a new one? 'Curious to know the outcome of that.

 

I would check the radio. The radio in my Jetta works perfectly when running, but has started drawing an increased consumption when the car is off (>0.5 amps) and will eventually drain the battery. This is the culprit in my instance.

Sean.

 

Thanks Sean, but he's already discovered the problem was with a bulb in the trunk.