Question:
No grounding white wire per video to put on grounding bolt from the module
asked by: Marty W
Helpful Expert Reply:
The Curt T-Connector Vehicle Wiring Harness # C55563 referenced in your question, which is confirmed to fit your 2005 Lexus RX 330, does have white wires on either side of the converter box. These are the ground wires, however the ground is already in the connector that runs to the existing driver and passenger side taillight ports on the vehicle. You will not need to ground the box beyond making these connections.
I have attached the complete written installation details on this harness that you can also check out.
Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector