Fuse #21?? and a dead battery

[Windfield]

Hello folks, I;m new here but have been working on my 1991 318is, first the waterpump and maybe a blown head, all's well now though. then a coolant leak in the heater tubing coming from the block,

The problem I have now is, a dead battery.

the current is flowing through fuse #21 to somewhere. I started the car the other day for the first time in months and the headlight switch was mixing up what to do, with the key turned off the light would be on in the off position and with the key on it was back to normal.... Oh yeah and the brake lights don't work but the switch and the bulbs are fine.... any help would be great.

Wind

[Windfield]

It was the Stereo, moister all over but it's the only problem.
from Mike B @ bimmerfest.

Fuse #21 provides power for the following: glove box light, rechargeable flashlight, ignition key warning, seat belt warning, all interior lights, memory for the radio, trunk lights, active check control, service interval indicator, OBC/digital clock/multifunction clock, and the tach & fuel economy gauges.

I would look first in your glove box cover where the flashlight goes. If the flashlight isn't there, make sure you don't have something shorting those two pins together. Also check the interior cabin lights above the doors. It is real easy to get one of the terminals shorting against the metal around the opening they fit into. Ditto for the trunk light. If that doesn't help locate the problem, I would start disconnect things one at a time. Leave the fuse out and the underdash plug/socket connected. Check for a short to ground at the fuse terminal after you disconnect one of the above. If the short goes away, you've found your problem. Put a good fuse back in and at least all of the other items will work for you.

Make sure your checking for a short on the cold fuse terminal, not the one with battery voltage on it. Putting voltage on your meter when your checking resistance usually destroys the meter.

Mike