how do i repair my draining battery issue

You have to find the short in the park light circuit, disconnect the headlight switch to see if it might be shorted, or it could be getting powered elsewhere in the circuit. Trace it out.

I have a 1998 740i bmw e38. Had the same issue. Come to find out the previous owner had replaced the brake light socket and bulbs with parts that where not original bmw light sockets. The computer didn't recognize the bulb sockets (they worksd) in place and thus a continuous battery draw. The original bmw bulb sockets do get hot and begin to melt however replacing them with after market parts (in this case) causes constant battery replace,ent. This was my experience regarding your questìn.