When installing the AP4-CH41 into vehicles with rear parking sensors, you may not hear the tones for them.
The reason being is they are not turned on in the module by default, and we will need to enable them. Below you will see how to do so.
Make sure to download the Amp Pro Application from the Pac-Audio.com website
Once downloaded, you will open the application and plug into the AP4-CH41 with it connected to the vehicle and with the key to the on position. Make sure you are using a Data Transferable cable, as a Charge Only cable will NOT work.
Go to the "configure" tab in the application and enable the rear chimes.
Once you have done so, simply unplug the AP4 from the computer and you are good to go!