TL;DR: Chatterbox filtering power cords blow a fuse in the newly installed circuit, and go to a dead short after that. So, I had been running a V-1, 2 Garmin GPS, and a Chatterboc GMRS X-1 off of the OEM GPS circuit on the new bike (2013 R1200GSW). This was basically working fine until I upgraded the V-1; the new V-1 apparently draws more power than the old one, and tripped the canbus, shutting it all down. That is what finally motivated me to install an Eastern Beaver (EB) "3 Circuit Solution One Fuse Unswitched Item# 3CS-1FU" (http://www.easternbeaver.com/Main/Wiring_Kits/Fuseboxes/3_Circuit/3_circuit.html) which is just a nicely done 3 circuit setup powered by a relay with the sensor wire tapped into a circuit that is only on with the ignition. Installing the EB thing seemed fine. No head-scratching or uncertainty. The main positive lead has a fuse and each of the 3 circuits has its own fuse. I tapped the same wire for the sensor that the aftermarket people all use for lights. I put in the main fuse, and a fuse in the one circuit that I planned to use for the 4 items. Made two sets of "1 to many" pigtails. One set red, one set black. The "1" end connects to the EB lead and the "many" ends connect to the various device power cords. I powered up the ignition and put a meter across the new circuit to see if I got voltage and to be sure I hadn't reversed anything. Tested fine: Battery voltage. Then I powered down, hooked up the "many" ends to the device leads and turned the key on again. POP! The fuse went on the circuit, instantly. Inspected existing wires from devices for abrasions, etc. None found. Disconnected all devices, replaced the blown fuse, then began to add the devices back on one by one, turning on the key after each to see if it was the problem child. It was all good until I got to the Chatterbox harness (http://store.valueaccessories.net/12voltdcpowerfiltercordforx1x2radios.aspx) (which was not connected to the GMRS unit at any point in this tale). Key on. POP!. I disconnected it and put my meter across the Chatterbox harness leads: dead short! Had another Chatterbox power cord on the other bike. Put the meter across its leads, and it was NOT a short. Transferred the other Chatterbox harness over to the new bike, connected it, key on, and you guessed it, POP! *DOH* Now, it too is a dead short. With a volt meter attached to leads on the new circuit, powering it up does not cause anything above battery voltage to display. I will call Chatterbox on Monday and speak with them about what might cause this, etc., but wanted to toss this out to the board to see if anyone had ideas about what is going on here. I could presumably run a new Chatterbox harness off of the OEM GPS circuit again and since that is what worked before, it ought to work again, but I am concerned that there is something going on here that I don't understand.