jbl audio system

I have a 04 tundra DC limited with jbl premium 8 speaker system. Have a Dual xvn279bt head unit with amp interface and stock amplifier. Sound was great but ever so often the volume level would increase and sound better for a short time. Volume suddenly dropped with distortion. Front door woofers were busted so I repaired them. It sounded great for about 3 minutes then lost volume like before. Installed bypass harness, took out amp interface, tied woofer speaker wires in harness to front and left door speaker wires. It has volume but is distorted and sounds like crap.
Any input would be greatly appreciated.

 

Would like to help, but having a hard time visualizing what you've done. Can you tell us what the part number of bypass harness you used, so we can actualy confirm it was the correct harness? And go into a little more detail on how you (A) ran the speaker wires and (B) made your connections, like did you solder, crimp, use wire nuts, etc?

 

Oh, and in case it helps, this is from the 1st Gen intro thread, the 2nd to last link "check this post" in this chunk of bullet point is pertinent to your needs:

• Before you install an aftermarket head unit, you need to identify whether your truck has the external amplifier, because you'll need to bypass it if it's there, else fade/balance won't work, or you just won't get sound! Read this thread for more info on the factory amp and where to find it if you have one, and what you need to do to install an aftermarket stereo. There are ways to retain the factory amp if you really want to, but ... just read that thread and its replies. To see what adapters you need (if you have an amp) check this post. To see what aftermarket radio others on here are running, read this thread. DISCLAIMER: Confirm fitment of any part numbers provided here by going to Crutchfield's or Metra's website before you commit to buying!

 

The bypass harness is a metra 70-8117. As for wire connections, they are twisted together, folded over twice then taped. After hooking up the bypass harness, it sounded ok for a couple minutes than no woofer. The back of the HU got pretty hot also. I'm thinking maybe the HU is bad?

 

That's absolutely not good enough, even worse than using a wire nut. You need to properly terminate your wires because the symptoms you describe could easily be a bad connection, although it could also be improper wiring. And you can totally blow stuff up that way.

They at least need to be crimped together mechanically. Whether you use a closed-end crimp or butt splice doesn't matter (shown in order here), but you need to use one for each wire, then tug-test the wires after crimping to make sure the crimp is solid.

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To do that, you'll want a decent set of crimpers, like the ones on the left here, NOT the ones on the right which are pretty much garbage you'll find in every basic toolkit.

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