There is usually a aux fuse block yes. Location varies, sometimes in the pillar behind and next to the drivers seat. On my van it is actually behind/underneith the glove-box (remove the plastic insert for the glove box and it's back there in the dash innards). Sometimes I've read where the things are in a even less sensical place and people have resorted to pulling interior panels off to follow wires. Good luck!
1991 Dodge B250 Zephyr Conversion. "Bi-frost" 74,000-ish original miles and counting. - 318TBI; has headwork and other bolt on upgrades. Runs strong and smooth! - Powertrax locker - 3" aluminum radiator. - Rear air springs, rebuilt suspension, steering stabilizer.