You didnt say whats wrong, but you cant have both wires of the RCA to the same splice. And dear god please do not use those taps or wire nuts. They are a little more expensive, but i recommend Posi-Taps.-Spliced both positive (pink and gray) and negative (light green and blue) to Red (positive) and white (negative) RCA interconnects
You need to run the Pos of the left RCA to the proper positive wire, then the Neg of the left RCA to its wire. Then repeat for the right side. It looks like you have the Pos/Neg to the same wire in the car.