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2007 Peterbilt 379 I have two sister trucks that in both have the same issue the factory stereo quit working, no sound from speakers, purchased aftermarket stereo and correct harnesses, but still no sound. units are getting power. Please help:)
December 13th, 2014
Common sense tells us that the factory radio was working but no sound.  2 issues possible can cause this problem and both are related to the speakers.  Trying 3 radios tells your power is okay on the truck to run your system.  The only thimg left is bad speakers..  Test the speakers to makes sure they are working and test the wires that connect all your speakers to make sure none show ground on positive or negative wires.  This would cause no sound in all radios.