According to our friends at Curt Manufacturing, part # C59236 is the correct wiring harness for your Lexus. The # 56201 is designed to be used with a multiplex wiring system like those found on some newer vehicles, and would not work correctly with your Lexus.
The harness would install as follows. The included circuit tester is used to test the circuits in the wiring harnesses that feed the rear tail light assemblies. As each lighting function is activated, use the tester to test each... view full answer...