From VSRI. I'll copy rather than link because phones don't seem to be working there right now.
3. Best places to obtain Switched 12 Volt power for an Auxiliary Fuse Block Relay.
A. Tail Light wire. This is the Brown wire running in the tail harness along the left rear subframe. It changes to gray under the rear fender in some models. Note: This wire is HOT when the key is in the PARK or ON position. This is good to use if you what to run accessories without having the ignition & lights on. But, if in park for an emergency and using emergency flashers your accessories will be energized. This is my favorite, but I also install a small underseat switch to disable the aux box when desired. Brown wire also avail under fuse box 05 & up 1000 & all 650. Eastern Beaver Kit.
B. OEM heated grip connector. Located behind radiator on left side & usually taped to the main harness. A Black connector with 2 wires going to it. The Orange/Green (white/green on 2014 and later DL1000As, or Veeks) wire is Switched Hot and Black/White is Ground. If you do not want to cut this connector, then order Suzuki part no. 36852-06G00 (~ $11). This is the horn lead wire on all but the Veek and the connector will mate. Eastern Beaver Kit.
C. Rear Brake Light Switch wire. Located just forward of the battery. A small clear white 2 wire connector, one Orange/Green (White/Green on the 2014+ DL1000A) & one White/Black. Orange/Green wire is switched Hot, no ground wire available here. Motorcycle 2.8mm - 110 Connector and Terminals
is one place to find matching connectors. 2 pin 2.8mm - .110 Male and Female locking connector is the one that matches and can be used to access a switched hot without cutting into the stock wiring.
D. Instrument Panel Power wires. Located inside left side cowling in wire pocket. Must remove cowling panel and strip part of harness cover off for wire access. The Orange/Green wire is switched & the red/white wire is full time power.
E. Any of the Orange (or striped Orange) wires under the OEM fuse box. You can just detach and pull the fuse box up to gain access. The Brown tail light wire is also here on 05 & up 1000 & all 650.