88 GTU
I'm trying to figure out the source for what's been draining my car battery. At first, I thought it was my alternator not charging my battery because after jump-starting the car and doing a few pulls, I turned off the car and tried to turn it back on with no success. I checked my fuses to be thorough and saw that when I took out the 60amp BTN fuse, my multimeter reading dropped from 100 mil amps to 20 mil amps, so I think I found the issue but don't know how to solve it from here. Can anyone help me?

 

next step is to go to the inside fusebox and pull the fuses on that BTN circuit, you'll have to look at the wire colors,

 

In my hunt for parasitic draw I found out a diode in the alternator had gone bad. I'd start there and work from the main fuse panel to the fuse panel in the interior.

 

What he said!

Set your multimeter like you did before, but instead of pulling the BTN fuse, pull one fuse at a time from the fusebox inside the car. Everytime you pull a fuse, check the multimeter. If there were no drops in the multimeter, put the fuse back in, and move on to the other.

Once you find the fuse with the substantial drop, you have to trace the devices in that fuse. You will basically be doing the same thing you did with the fuses, but this time around you will be disconnecting devices from their plugs and checking the multimeter for the substantial drop.

I had to do this process, in my case, it was one of the headlight motor. What I learned is that the headlight motors need to complete their cycle/motion. If they are not fully "engaged" or "disengaged", the motor will keep trying to reach is complete cycle constantly, even if the car/engine/key is off.