At least one answer is in my post, "D558BT Limited install w/rear speakers." You will not get rear speakers with that harness or any harness as numerous posts indicate (if you have the original nav head unit). You have to tap in at the amp with jumpers or bypass entirely as I did. Worked for over three hours with Crutchfield reps RJ, Casey, and Vince, and the final result was that they recommended that I return the HU because the wiring specs in the service manual were too messed up to use, and also that there was no plug and play option with any harness.