WARNING: This page is about a different car, the 2016 Jeep Wrangler and 2015 Jeep Wrangler. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes
(X300) AMPLIFIED SUBWOOFER 1 (+) CIRCUIT SHORTED TO THE (X390) AMPLIFIED SUBWOOFER 1 (-) CIRCUIT