T680 subwoofer

They have a subwoofer? I've never heard mine woofing.

 

I tool around in a '16 Freight.... The bass output on the rear 6x9's is enough to rattle me out of there... doesn't help that my head unit is possessed and goes from volume 12 to 30 without my touching it sometimes.... accursed thing.

 

My 680 has no bass. Period.

 

If the head unit is working, looking at the fuses on the back of it is a waste of time.

If the fuse for the OEM subwoofer amp is not blown. Your next step is to check to see if the subwoofer amp is getting power by using a testing device. Also testing the subwoofer speaker may need done. (Checking the connections at the speaker. A simple 9 volt battery is all one needs to test a speaker.)

Having a subwoofer is great for movies as well.

 

Don't know if you ever found the problem or if you even still have this truck anymore but I had the same problem. But it wasn't just the sub. It was the other 2 speakers on the back wall in the sleeper as well. I figured someone turned them off because they were running team so I played with the radio settings. Turns out there's a 2ch or 4ch setting. Mine was set to 2ch. Changed it to 4ch and now both speakers in the sleeper as well as the sub are working fine, and sound great. To get to the setting you just hold down the volume button until a menu with 3 options pops up. Select the "speakers" setting and tap the volume button to select it.