Pioneer AVIC-F920BT - Manual (Page 13)

Power cord
Violet/white (REVERSE GEAR SIGNAL INPUT)
This is connected so that the navigation system can detect
whether the vehicle is moving forwards or backwards.
Connect the violet/white lead to the lead whose voltage
changes when the reverse gear is engaged. Unless
connected, the sensor may not detect your vehicle
travelling forward/backward properly, and thus the position
of your vehicle detected by the sensor may be misaligned
from the actual position.
When you use a rear view camera, please make
sure to connect this lead. Otherwise you cannot
switch to rear view camera picture.
The navigation unit
Note
Engb
13
English
Section
03 Connecting the System