QUOTE(Dennis the Mennis @ Aug 21 2008, 07:21 AM)
Better to use a tester (AutoZone has them) because the wiring guides are often wrong or difficult to interpret. Start with a turn signal and probe the wires in the trunk until you find the one that flashes your tester to the beat of the directional.
Fair warning: the Sonata uses something called "Negative Triggers" for all lighting. You won't be able to wire your trailer directly to the cable. You need an adapter (it's sometimes called a "diode bridge") between the wires in the trunk and the plug for your trailer. The shop where you bought your trailer hitch should be able to help.
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I would assume by diode bridge, you mean the harness I got from my dealer. It takes the 3 circuit system in the Sonata (Brake, Turn, Running) and creates a two circuit (Brake/Stop & Running) system. I finally came to the conclusion that I would have to trace all the wiring manually and this is the week-end to get at it.
Thanks for the info.