Review on IDataLink Maestro HRN RR GM5 GM5 T Harness by Josh Zuvers

This is a lifesaver! I went to their website and the diagram showed me how to connect everything - remember it's universal so depending on the make/model you may not be using all the cables included. This includes an OBDII connector so you don't have to manually connect your vehicle's wiring - in my case the only wires I had to manually connect were on the head unit wiring harness. The cables for the speaker and the OBD-II connector were also very long, making it easy to route them anywhere in the car.