Possible Causes

WARNING: This page is about a different car, the 2012 Dodge Charger. However, it is still accessible from the selected car via links, so may be relevant.

Possible Causes
(X303) LEFT REAR SPEAKER (+) CIRCUIT OPEN
(X393) LEFT REAR SPEAKER (-) CIRCUIT OPEN
LEFT REAR SPEAKER
TELEMATICS GATEWAY (TGW)