OOh... you have the 3rd wire which is for DRL right?
I use a cheap multimeter and set it to continuity check. One probe on the chassis, and the other to probe the terminals inside the bulb socket. If you hear a beep, that's the ground wire. Set it to VDC for the voltmeter and probe the remaining terminals while the blinker is active, and you'll know for sure which one is the turn signal wire. That's when you solder both ends of the resistor to those wires.
Another check is to plug in the LED bulb and make sure it lights up. Remember the orientation, pop off the bulb or get another one, and rig up a 9V battery to get it to light up, and from there you'll know the polarity matching the terminals in the socket.
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