Just finished hooking up the OEM camera to the Z110BT. Took me 5 hours but most of that was education unwanted, also had to join TIS for wiring/connector help.
The Venza has a multifunction display (TFT) up front that the camera is connected to. You just need to splice into 3 wires, 2 for the camera and 1 for the reverse signal.
The connector at back of TFT is F1. #14 = Red to Vid + (pin on the rca) #15 = White to Vid - (shield on rca)
#2 = Gray to purple/white pioneer harness.
P.S. I tried to use pinouts and wire colors from a post in the Tundra forum, but they were different from the Venza.