First Impressions

[ULEWZ]

Yamaha will have some fly leads hidden under the plastic, I think under the screen hardware on the FJ. These are usually 4 way Sumitomo plugs. There will be one for the heated grips, one for the accessory lights and another for the second accessory socket. 
The heated grips & lights plugs will have 4 pins - one earth, one live with the ignition on, one live when the engine is running (i.e. headlamp relay on) and one wire that returns to the ECU.
 
I know this from my Super Tenere which has the same items in the accessory range. I identified each wire using a multimeter and trial and error. My BTeC in electrical engineering finally came in handy.
 
I fitted my own heated grips to the Super Tenere tapping into Yamaha's harness. The mating half of the connector is already there, you just need to find suitable pins to solder onto your wires and pop them in the holes, or just cut off the Yamaha plug and solder or join the wires using some other connector. Self amalgamating tape will waterproof any connections.
 
Edit: make sure any accessory lights are wired into the same circuit as the headlamps so you don't put the tiny battery under stress when starting the bike

The factory FJ-09 heated grips must be wired a little different then the Super Tenere as there are two separate plugs for the grip heaters. One White plug and one black one. 

 

[wessie]

Bear in mind my XT1200 was the original model. They changed the display to the same unit as the FJ from 2014 onwards so may have changed the wiring to match the display requirements. The "plug & play" principle still applies for Yamaha's accessories.

[johan]

@johan - seen this Tutoro oiler, or do you already have the Scottoiler? I have it working on my bike. Seems to work well and no electronics or vacuum needed. I have not posted a review as it is in a state of temporary attachment with zip ties as I need to find where the luggage brackets go before deciding on its final position.  
Tutoro are based in Lydney, Gloucestershire, about 40 mins from where I live on the other side of the same county.
 
Weather: cloud breaking up now so once I have watched the F1 GP replay I might get a ride on the bike. 

Thanks, I saw your Tutoro oiler and I like it for the same reason. Please do provide a review when ready. I have not purchased the Scottoiler yet, and the eSystem is very expensive. I considered it as it is supposedly more accurate and less messy than the vacuum system. It also does not dispense oil when stationary. I park in the basement at work and don't want to leave too much of a mess.

[wessie]

I'm getting little mess - just the occasional drop off the front sprocket which is going to happen even with the e-system. I run it quite lean so that there is just a visible gloss on the O rings.
 
I just stick a bit of cardboard under the bike to catch the drip as the bike is in my en suite garage