am towing a 1997 GMC Sonoma. Battery dies when I tow. I believe this is because the instrument panel is electronic and the heater always runs when the key is in the accessory or on position. Also, my speedometer registered the towed miles. Someone said I could pull a fuse to eliminate this problem. Which fuse should I pull? Or would it just be better to disconnect the battery? If I want to disconnect the battery, where can I find some kind of a disconnect device?