Self-employed

Vehicle bought brand new Feb 8/2019 its a truck, 10.1 class. costed before taxes, $50,224.08.  CCA for the year is $2,330.08. Total business km's was 10,920.  total km's was 23,831. Business use is 45.8227%. I selected  "Add vehicle for business use" as it is just me and nobody else doing food deliveries with it. So if i am not claiming CCA do I NEED to enter the info in the CCA chart? WHY does it make my refund become LESS if I enter the info? is it because its an asset? I don't understand why they deduct $ from my refund when its not being claimed? Id like to obviously get the biggest return possible, but if I don't enter the CCA chart info I don't wanna get in trouble with CRA for it? AS well, next year I will maybe wanna claim CCA? Is it possible to claim 2019 and 2020 CCA when I do next years if I owe next year?