Adding Interior BSM Indicators

The reason I am attempting this project is that I have come to the conclusion that the Blind Side Monitor (BSM) indicators are too far outboard on the exterior mirrors to be easily seen. I thought this project would be fairly easy since I have a damaged driver side exterior mirror on which to experiment. The BSM indicator on it was working at the time it was replaced. Not so fast! I though it would be a matter of just splicing into the two wires leading to the BSM indicator on the mirror glass to power an interior LED BSM indicator.

What I tried today was to see if I could establish continuity on the two wires/pins of the mirror's BSM indicator with a 3-volt lighted continuity tester and to see if I could get the BSM indicator in the mirror glass to glow at least a little. I failed on both counts. I'm now wondering if this is some sort of CAN Bus LED circuit that is beyond my abilities. Surely three volts of power would be enough? Too much?

The 1st of the attached three photos shows what I eventually hope to accomplish - an additional LED BSM indicator on each side of the interior. (Photo borrowed from Consumer Reports.)

The 2nd photo shows the front of the "cadaver" mirror glass I'm using for experimentation.

The 3rd photo shows the back of the mirror glass, the location of the BSM indicator and the connector that has wires that lead to the BSM indicator. I bridged the two pins leading to the BSM indicator with a 3-volt continuity tester. I didn't see see any other wires attached to the BSM indicator.

Does anyone have suggestions on what to try next or do differently? (other than psychiatric care?)