Yes the B is for Battery, (I) ignition and (A) accessory. You can test the switch just to be sure by connecting a full time power supply to the (B) terminal on the key and they turning the switch to the on position which should give you current to the (I) terminal. Turn the switch to the accessory position will give you current to the (A) terminal and nothing to the (I) terminal.

The brake fuse is full time battery supplied current so it will be hot all the time.


Joe