I have a 2004 Honda Accord and I am having issues with something draining the battery. I have figured out if I remove the fuse under the hood labeled backup, ACC, the issue goes away. I do know that fuse controls the radio, door locks, cab lights but not sure exactly what else. It has an aftermarket radio and I have read that bluetooth can cause issues. Don't believe that to be the case. I removed the aftermarket radio and it has a 10 fuse on the back of it, removed that and there is something still drawing power. So guessing that completely rules out the aftermarket radio and bluetooth. Now it still has the factory radio installed, done by previous owner. It still shows the time and can turn it on, just don't have any sound from it. With the backup, ACC removed, its completely dead. I have not took that radio out yet but guess that will be the next thing I check. If that is not it, any idea where I should look next? No lights are staying on that I can see. The battery is about 3 years old, replaced the battery before I figured out there is something draining it.

 

You'll have to do a parasitic draw test on the car. You could have more than one fuse/component contributing the current draw. A quick check is to measure the voltage drop across the top of the fuses. A more detailed check is to hook up your voltmeter between the battery and the negative (or positive) battery cable and pull fuses while watching the current. You need to use a clamp to hold in the door switch, so the door and dome lights don't blow the fuse in your volt meter. Once you determine only the acc fuse is the culprit, you would have to unplug each component on that circuit to determine what component(s) is the culprit.

Pine Hollow Diagnostics or South Main Auto have some good videos on youtube for finding a parasitic draw. Schrodinger's Box is another good chanel.