Installing a set of Truck-Lite LED blinkers on my A3 today. How do the wires match-up? The light has 4 wires: ground, green/483/484, blue491, and red 460/461. The truck has 461, 491 and 20. Do I plug 20 from the truck into green/483/484 on the light or is 20 the ground? (The original light had 3 wires and LED has 4. Thanks!