In a large bowl or mixer, mix cake mix, water, eggs and melted butter together, then stir in 1 cup crushed pineapple, coconut and pecans until incorporated.
Liberally grease a slow cooker with non-stick spray, then pour batter into cooker and smooth top layer with a rubber spatula.
Take two layers of paper towels and place over slow cooker with ends extending out over the sides, then place lid on top of slow cooker. (This ensures that the paper towels absorb all condensation, instead of dripping down onto the cake.)
Cook on high for 2 hours or on low for 4, leaving lid on the whole time.
In a medium bowl, whisk together glaze ingredients (powdered sugar, pineapple and pineapple juice, butter, coconut and pecans) until smooth.
Uncover slow cooker (making sure cake is cooked through), remove paper towels, then pour glaze over the cake, cover again and let set for 5-10 minutes.
Scoop, serve and enjoy.