I found a website that has what appears to be the factory service manual for 2015-18 Chargers. The manual is broken into numerous parts and can be viewed either online or you can download each part as a PDF.
Here is the link: Dodge Charger 2015-2018 Service Manual + Wiring Diagrams | Free Download
Here is the link: Dodge Charger 2015-2018 Service Manual + Wiring Diagrams | Free Download