I am assuming this is a van with the Infinity system. The blue wire that is marked in most instructions as the power antenna is in reality the 12V feed to the speakers (they are amplified). Hook this to 12V and you will have your bass and audio from all the speakers.
Craig

2014 Ram 1500 Laramie, 73 Cuda
Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango
Only previous Non-Mopar: Schwinn Tornado