I have two Priuses: a bare bones 2010 and a top-of-the-line 2009. The 2009 has a Homelink rear view mirror that I'd like to move to my 2010 before I give the 2009 to my grandson. Anyone know if I'll find the unused Homelink wire harness parked in the 2010's head liner above its rear view mirror? The existing 2010 mirror has no electrical connection to it.
I eventually answered my own question posed above by removing the overhead lighting assembly in the 2010. There is not an unused wire harness in bottom-end 2010s that where shipped without the HomeLink mirror. Nor is there a supporting connector on the overhead light assembly's circuit board to permit connection of the electronic mirror. My guess is that Toyota made customized wire harness assemblies for those Gen 3 Prii that had the electronic rear view mirror. I took the 2010's overhead light assembly to my office lab and reverse engineered it. There is no ignition-switched +12V in that assembly that could be used to drive the high current portion of the electronic mirror (the dimming subsystem draws ~80mA). However, there is a white LED in the light assembly (map light?) that is driven by a green wire from the ECU. This green wire is "hot" whenever the headlights in the vehicle are on. I used the green wire to power the dimming subsystem in the electronic mirror.