My Honda 2000 has an electrical problem, but no one, including the Honda dealer, can tell me what the cause of the constant drain on the battery. If I leave the car sitting for over 48 hours the car does not start. I’ve placed a new alternator and that doesn’t seem to solve the problem. What could be causing this problem?
If your battary is good and the alternator is charging properly, then you have a residual drain or parasidic drain, which means something is sucking power when your car is parked. You can loosen one of your battery cables, and see if it makes a spark when you barely touch it back to the post. It probably will. Then pull your fuses one at a time, performing the battary cable to post touch, until you find the fuse that makes the spark much smaller. Once you find that, you’ve narrowed your search down substantially. Now you have to check everything in that circuit. If you had a good current meter, you could do the same thing, but I gave the definition for troubleshooting without specialized tools. Or you could crawl in your trunk and have a trusted friend promise to let you out and see if the light stays on with the trunk shut. Or check your glove box light, or under the hood light, etc. It’s usually something pretty simple.
Follow the trace instructions. Sometimes a bad door switch will cause this since the circuit does not close correctly when you close the door. Badly installed aftermarket amps also cause this by leaving the amp on.