Pancakes can be made from cake mix, but only adding water to the mix will result in an odd consistency. The other ingredients such as eggs and oil should also be used.
Pancake Mix Versus Cake Mix
Pancake mix and cake mix are similar in many ways; they both have flour, sugar, a leavening agent, and salt. However, pancake mix generally has less sugar and has the shortening (or oil) already added into the mix. Pancakes made from a basic pancake mix still call for eggs and milk or water, while a complete pancake mix generally only calls for water or milk. The complete mix already has powdered egg in it, which is why you don't need to add it.
Eggs and Oil or Shortening in Baking
Eggs are useful in baking because they add structure and leavening. The protein in eggs helps hold the pancake or cake together so it doesn't fall apart. They also assist the baking powder or soda in making the product rise, as well as help the oil and liquids in the recipe blend together. The oil or shortening adds flavor as well as moistening the pancake or cake.
Using a Cake Mix Without Oil or Eggs
If only water is added to a cake mix to make pancakes, the result will likely be something like a pancake. However, it will be more crumbly, due to the lack of eggs, and have less flavor. Also, it will likely be drier because it doesn't have the oil.