Here is what I found installing an OBC on my 2k LT that didn't have one from the factory.
The OBC frame harness connector was present, temp sensor connector was present.
The BC switch is not on the RH multi-function switch if OBC not factory installed.
The dash is different on the factory OBC equipped models, 46632347318 instruments cover (BLACK), is the proper dash cover.
The outline on the non-OBC factory model dash is larger than opening necessary to install the unit. (don't ask me how I discovered that!!)
The factory BC switch on the RH multi-function switch connects to the OBC unit at the electronics control unit under the tank.
If you could find a pancake style momentary switch it would fit inside the RH multifunction housing.
How I installed the OBC w/temp sensor -
Cut out the dash to accept the OBC
Glued plastic spacers on the back of the dash so the metal clips on the OBC unit will 'latch' behind them. Used silicone around the inner surface of the OBC flange to add some support.
Installed a momentary contact switch between pin #1 (brown/black stripe) and pin #6 (brown, ground)
I put the momentary switch to the left of the dash courtesy light; not super convenient but it works.
Installed the temp sensor bracket to the bottom headlight screw.
Appears to be working!