The last of the Four Reliances is "Rely on wisdom, not on consciousness." Sometimes that is translated "Rely on wisdom mind, not discriminating mind." I'm sorry I couldn't find a Sanskrit version to pick apart and maybe tie down the words more precisely. But this is arguably the clearest of the four.
Taken together, the Reliances describe a path away from our illusory projected "reality," beginning with reliance on the dharma. The Reliances warn us not to be sidetracked by a teacher's charisma or by words that seem to answer our spiritual questions but which don't impart any real wisdom.
In Theravada Buddhism, wisdom (panna) is associated with discernment and freedom from "mental fermentations." The fermentations are thoughts, especially thoughts that discriminate and speculate. In Mahayana Buddhism, wisdom (prajna) is associated with the realization of sunyata, or emptiness.
I think both schools would agree that "wisdom mind" is a mind clear and free of unnecessary thoughts, opinions, biases, and expectations. And this fits nicely into the recent discussion on the koan "Ordinary Mind Is the Tao." In the words of the late Robert Aitken Roshi, "This constant 'ordinary' is not the commonplace mind of self-centered preoccupation. Selfish conduct, speech, and thought obscure the vast, moonlit mind of Nan-ch'uan."
Most of us stumble through life relying on a tangle of assumptions, projections, and confirmation biases to find our way around and make sense of things. Buddhism challenges us to let that drop away and rely instead on clarity, without clinging to views and opinions.
And this takes us back to the beginning -- rely on the dharma.