The PX6 which don't have Backup Camera after installation could try following solution:
Go to setting- Install set- password 8861 or 666888
If the backup camera are connecting with RCA connector, no matter it's original backup camera or aftermarket backup camera, the Setting for Reversing Video Format need to choose CVBS-AHD Signal.
If the backup camera connecting to the LVDS line, the Reversing Video Format need to choose VGA-YUV signal.
The unit using the LVDS lines are the unit that retains Sync2,Sync3 module like: 14-18 Silverado, 15-18 Colorado, 15-19Tahoe, 15-19Mustang, 15-19 F-150.
If above setting not working
Go to setting- system info-press and hold for 5 second- insert 7890-go to user setting
If the unit retains the OEM LVDS like Chevy, Ford F-150, Q50, Silverado, Colorado, Tahoe, Mustang, Cadillac, Using 8836 Interface-On
Plug HD 360 - OFF
When connect the backup camera with RCA, check the label on the both RCA connector. Normally the label should be Camera(Cam V in, Camera in, Reversing Video In) Connect to the RCA labeled Camera.
The Unit retains sync system need to take out the Sync module in from the OEM unit and put on the back of the Unit. The connect to the LVDS line to Both Unit and the Car to get the backup camera.