Oh! good point Cherr! I noticed. I believe the white strip is ground and the solid black is positive on the LED strips. I had troubles with them and found out that they are like that. You would think the solid black was ground (according to standard DC wiring, black is ground), but I do believe it is positive.
Went out and looked at the car (wife had it), and it shows the passenger side being the darker blue wire. there are two blue wires that run to the back, one is sky/baby blue, and the other is just blue. The regular blue wire is the one you want... The other side is a blue/black wire. The ground is definitely black going to the signals.
Also, a good rule to follow when dealing with prewired LEDs and LED strips.... Have a 9V battery handy to check which is pos. and which is neg.. This has saved me a lot of time in the past.
I've come across situations where some prewired LEDs were wired backwards.