Ditto same issue with my 2015 1500 Laramie Alpine system. Noticed it after having the sub unplugged for a week while doing rear window slider work. Had truck in ACC mode to exercise pwr window so stereo was powered up w/out sub connected too. Plugged sub back in & sound system had tinny sound. No changes made to UConnect audio settings & old settings confirmed same as before sub disconnection. Tshooting so far: adjust balance to isolate each speaker, amp fuse F71 good, soft reset of UConnect system (push & hold Volume/Mute & Tune/Browse knobs in simultaneously 12+sec) done successfully - front door speakers both silent still. Overall sound did seem a little fuller post soft reset but both speakers still dead. I welcome input. Next steps: UConnect hard reboot (disconnect battery for several hours), swap speaker with known good speaker ( I have a spare dash speaker from 2018 upgrade).