I have a bunch of LED's that I am going to use for my side markers so that I can have them on and blink at the same time. I'm going to wire both of the LED wires to a + (+ parking light + blinker light). Would I need a resistor on both of the wires or just one would be fine?

 

you will need a resistor(s) for both. Its better but not required to put the resistor on the ground side of the LED. for making your array, use this wizard. very helpful.

http://led.linear1.org/led.wiz

 

I've been thinking about doing something similar. I believe you will need a resistor on each power source, and a diode on each to prevent feedback between the parking light and turn signal circuits. Otherwise all four corners will get the power when you activate your turn signal. Also, the resistors will need to be different ratings, with less voltage going to the parking light part. Then when you put on the turn signal the diode would stop the current from going back through the parking lights and be brighter because of the higher voltage.

I am NO electrical expert, but I do enjoy tinkering with LEDs and this is what I've been thinking about. I could be FAR from right and hopefully one of our resident electrical engineers could steer us straight if I am off base.

I recently bought a circuit board to mess with and I'll post up if I get a solution.