Back-up Light Circuit: Description
WARNING: This page is about a different car, the 2008 Toyota Yaris. However, it is still accessible from the selected car via links, so may be relevant.
A/T models: The park / neutral position switch turns on when the shift lever is moved into the R position, causing the back-up light to illuminate.
M/T models: The back-up light switch turns on when the shift lever is moved into the R position, causing the back-up light to illuminate.