Slow drain on battery - it only happens when the car sits for 2 days and after 1.5 days battery is almost dead. It's the same on a new battery, so somewhere current is leaking. A battery disconnect switch solves the problem, but I'd rather fix it. My mechanic has seen this problem 3 times on 740 wagons only. The only other similarity is that these cars have hitches installed and are wired for hitches. Are there any live wires that could drain the battery through the light splitter? What else goes wrong with these 740 electricals that drains very slowly? I have yet to test at each fuse for current, would that work? ideas..?? thanks!

look here from two minutes ago:
http://www.brickboard.com/RWD/volvo/1419422/740/760/780/89_740_gle_electrical_drain_alternator.html

I believe this is how you test (or something similar): Disconnect negative battery terminal. Connect a test light between the negative cable and the post itself. Test light should light up because of the drain. Then have someone pull fuses one at a time. When the light goes out, you will no which circuit is causing the problem. With a 240 that I have, it was the power door locks. Good luck.