* Factory Radio Settings: The most likely scenario is that the rear speakers are simply turned off in the factory radio's settings menu. Look for options like "Fader," "Balance," "Speaker Configuration," or similar. Experiment with these settings to see if you can route audio to the rear. The manual for your specific radio (the model number is usually on the faceplate) will be the most helpful here.
* Head Unit (Radio) Replacement: If you have an aftermarket radio installed, its settings will control rear speaker output. Consult the manual for that specific unit.
* Wiring: In rare cases, the rear speakers might be improperly wired or have a faulty connection. This would require checking the wiring behind the radio and at the speakers themselves. This is best left to someone experienced with car audio. A blown fuse dedicated to the rear speakers is also possible.
* Bose System (If Equipped): If your Suburban has the optional Bose sound system, the settings might be more complex. Consult your owner's manual for specific instructions. The Bose system might have more sophisticated equalization controls that could be affecting the rear speakers.
In short: Start by meticulously checking your radio's settings menu. If that doesn't work, consult your owner's manual for the specific radio and/or sound system installed in your Suburban. If you're still having trouble, consider seeking help from a car audio professional.
