hiiya1

I'm having an issue with the battery on my 91 RX7 convertible going dead over night. I found that it was a 7.5 amp fuse that was causing it to go dead. The fuse is marked "Room" on the fuse box lid. It appears to affect the interior lights, ignition switch light, exterior door light and also my radio and clock. I don't have any idea what caused it as it just happened overnight. I was told that it had something to do with the alarm system. What can I do to alleviate this problem? Any assistance will be greatly appreciated.
Thanks,
Ray Brown.

YellowT2

iTrader: (1)

I'm assuming you checked that none of the lights powered by that fuse are on? Interior lights, ignition switch light, trunk light, etc. I'm not sure exactly what that fuse powers, but looking at the FSM wiring diagram should tell you.

If it's not a light, then you might need to start unplugging things one at a time until the drain goes away; then you know what is causing it, so repair/replace that component.

hiiya1

Yes all the lights that are associated with this fuse are off. When I pull this fuse the drain goes away. I have pulled every fuse to see if anything else is causing the drain and nothing is. Although there is another fuse for Audio when this fuse is pulled the radio will not work. With this fuse pulled the car starts and runs as it should but those lights are out and so is the radio.

YellowT2

iTrader: (1)

I think you need to start unplugging stuff until the drain goes away. Do you have a multimeter/ammeter? Disconnect one of the battery terminals and connect the meter between the battery and terminal, so you can see the current draw. Go through each of the circuits connected to the ROOM fuse and unplug them one at a time until the current drops significantly.

According to the FSM the circuits I see coming off the ROOM fuse are:

• Lamps (cargo room lamp, courtesy lamps, door lock key cylinder illumination lamp, ignition key cylinder illumination lamp, room lamp, spot lamps, trunk room lamp)
• Sound warning control system (CPU)
• Engine Control System
• Shift Lock System
• EC-AT Control System
• Warnings & auto clock
• Audio System

Regarding your comments on the audio system: the ROOM fuse provides constant power to the audio system, and the AUDIO fuse provides ignition switched power.
This is the same for a lot of the electronic components (CPU, ECU, EC-AT system, clock); the room fuse provides constant power (to maintain memory settings, keep the clock running, etc.) and a separate power line (either ACC or IG1) provides the main power when the car is running.
I think any of those components could have an electrical issue causing a power drain (like internal corrosion causing a high-resistance short; not quite enough to pop the fuse, but enough to drain the battery), so it's up to you to test and see which one.