Welcome to 2CarPros.
First, I attached pictures from the schematic. I highlighted the power supply from the BCM to the light. If you have power at the BCM (see picture 1) either there is a break in the wire or if there are folding mirrors on the vehicle, there is a splice under the dash in the wiring harness that may be bad. I put the pictures in order and overlapped them so you can follow the schematic.
Take a look through these pictures. The blue and white wire you referred is highlighted in yellow. Also, I circled the splice I am referring to.
Let me know if this helps or if you have other questions.
Images (Click to enlarge)
Wednesday, May 15th, 2019 AT 7:33 PM