GMC 3500 HD Door Illuminated Sill Plate Instructions

[AlaskaTrip]

I’m trying to find instructions for how to install a set of illuminated door sill plates for my 2023 GMC 3500HD Denali.  The GM part number is GM#85136964

 

I  found all sorts of instructions for other models. But can’t find the one for this. 
 

I can’t figure out where to connect the wires on the drivers side under the dash.  There is one specific wire I’m supposed to cut and splice this harness in to but I don’t want to cut the wrong wire .  
 

Anyone have access to GM Service Information (S.I.)?

 

Thanks for the help!!