Putting my farrin and headlight back on my 2008 ultra classic. need a diagram for headlight assembly. i have a peice of wire that i dont know what to do with

Shown here. Power is the orange. Ground is black. Signal is Yellow.

https://www.hdforums.com/forum/dyna-glide-models/687505-fuel-gauge-wiring-confusing-2.html

https://www.google.com/search?q=2003+Harley+Davidson+Ultra+Classic+Wiring+diagram+for+the+fuel+gauge

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I have a wiring diagram for a 2008 FLHRC, maybe it close enough for you.

The rear injector has a green wire and a yellow wire with a green stripe.

The yellow/green wire runs back to the fuel pump fuse (15 amps)
The green wire runs to the ECM (pin 23)

Does this help?
If not, give me more info.

I also have the diagnostic trouble code flow chart if that would help.

Yes you can replace just the switch on your bike. I would guess that the switch is the same as a flhtcu on your trike. Here's a link to Bike Bandit with a drawing of the switch housing and the switches that are in it. http://www.bikebandit.com/2008-harley-davidson-touring-ultra-classic-electra-glide-flhtcu/o/m18634#sch624738 This is a 2008 model but I would also guess that it's the same switch. You could compare the part number at your local dealer to find out. Or, you could just buy the switch from the dealer and use the diagram for information only.

Good Luck
Steve

yes because you will have to run wires from the front to the back for the speakers unless your really good at wiring