An aftermarket module arrangement for installation into a vehicle having a vehicle bus and an electric power source is disclosed herein. The arrangement includes, but is not limited to, a module configured to communicatively couple with the vehicle bus and to electrically couple with the electric power source via a first electric power line, and further configured to engage in power line communications over the first electric power line. The arrangement further includes an aftermarket module configured to electrically couple with the electric power source over a second electric power line and to engage in power line communications over the second electric power line. The aftermarket module is further configured to communicatively couple with the module via power line communications and to communicate over the vehicle bus through the module.