Start with a multimeter or test light on the battery. Run it in line with the cable. With the key off the light should only stay on for a split second.

If you have a short it will probably stay on indefinitely. If you get to this point then you can start pulling fuses to narrow down which circuit has the short. Since the windshield wipers are acting funky, start with that fuse. When the light goes out, you have found the circuit.

1992 VR4 12.5 @ 110 - SOLD
1993 Stealth RT/TT 11.4 @ 129 - SOLD
1991 VR4 9.2 @ 159 - Old Shop Car
1992 Stealth Twin Turbo ATX - SOLD
1990 Montero LS LWB - RIP
1995 Montero LS - RIP
1998 Montero
1992 Galant VR4 474/1000
2007 Prius