What does consciousness have to do with reasoning? You're conflating two different things.
Consciousness is the what-it's-like of sensation you have as an organism from your sensory modalities and having a body. For human, that's colors, sounds, tastes, smells, feels, feeling of balance and what not that happen in perception, hallucination, memory, imagination, inner dialog and dreams along with emotions. Each sentient organism has their own sensations and emotions making up subjective experiences that nobody else has access to except inference from behavior and language (for humans).
That's not reasoning (just the having sensations/emotions). Reasoning is an adjacent activity that can be conscious but also unconscious. And it's hard to say that colors, sounds, emotions are illusions. What does that mean? We do experience them. There is something it's like to see color which is different from what it's like to feel pain or to be in love. And none of those (presumably) are what it's like when a bat experiences echolocation (there are many examples from the animal kingdom if one takes issue with echolocation).