Jason,
The test light placed in series with one of the battery cables is a good and safe way to check for current flow. Since the test light only requires a tiny bit of current to illuminate the bulb, it is a poor way to determine the amount of current flow, or the severity of a short circuit or other circuit fault.
A multimeter installed in place of the test light will give you a better handle on how much current is flowing, and while you go about trouble shooting the wiring harness and or pulling fuses, any changes in the amount of current flow will be noticed immediately.
Pulling each fuse (and leaving it out) one at a time will allow you to see the current draw for each fuse. Do this test with the ignition switch on, and again with the ignition off. Ideally, with the ignition off, you shouldn't have any current flow at all. If you have a radio with memory, or an electric clock, or any other device that requires a constant supply of 12 volts, than you must determine if this current demand is "normal" or too excessive.
Also, check the alternator and regulator. The hot lead from the alternator usually connects directly to the junction terminal on the solenoid, but maybe yours is connected somewhere else, and is causing this drain.
These problems can make you pull your hair out, but hang in there and try to take a logical and systematic approach to locating your problem. And don't arbitrarily assume that any recent rework is not to be suspected. Go back and double check what you did to see that you did it according to the directions..... you did read the directions didn't you?
Good luck
- Jim -