delicacy of usb ?

I have a 2012 scion tc, and the usb power is pathetic, so I tried to re feed it with a 5v,3a source, I just sliced into the cable and cut the 5v line, splicing my 5v to the port, leaving off the original It didn't charge or enumerate at all, I put it back to the original 5v thinking It needed it somehow, but still now wont enumerate, I guess since I parted the shielded braid that could be the cause of failure? The data lines are foil covered wire, ony the 5v line comes out of the braid since I had to solder it could that be the reason? I did it all without power on so I doubt I shorted something

That’s too bad. It might just be the USB cable. Did you try a new one?

Also, not that is makes any difference now, but I never run my boards off USB. To me, it’s just a bad practice. My advice would be for you to get a 9V 1amp switchmode wall-wart and use it all the time.

Its actually for my phone to charge, being it draws over an amp and the cord works in a regular charger, and used to work in the usb port once it said charging but only for a second and it will wake up the screen when I plug it in but doesn't say anything

The braiding was probably ground. Where did you connect your 5V supplies' ground?

The wire they use in USB cables are hard to solder and easy to break, looks like you broke it.

and it will wake up the screen when I plug it in

It will do that if there is any sort of load on the data lines, it doesn't mean very much.

Ill have to cut open a usb cord and check the lines, I was very careful not to break any wires, I ony parted the shielding and cut/pulled out the 5v a bit the shield is connected to the separate negative wire for the port, which is connected to the cars ground, where my power supply is connected I thought perhaps with the break in the shield and the switching power supply it was interfering, but even put back it seems to have been damaged, there isn't any visible damage to the wires, although if I can't figure this out I guess ill have to cpnvert it to a dedicated charging port

I have a 2012 scion tc

Link to this? I only found car reviews.

It is a new car, nm about it online to my disappointment, im slowly making it better with little gadgets, latest being an arduino lights controller to control lights in relation to the music playing, But its less about the car I would think than regular usb problem, perhaps more noisy an enviroment

Well there are USB gadgets that plug into the cigarette lighter and which could be used to charge your phone. For example:

http://www.jaycar.com.au/productView.asp?ID=MP3662

I have a car charger which works ok, but why should I have to when my car came stock with a usb port? When I have my phone plugged in to a usb port with data lines shorted my phone will draw over 1 amp to charge, the stock usb didnt charge enough to prevent it from dieing I think I may have to buy a new male end and redo the connection,

You should connect the supply to both power wires within the braid, not just the +5V one. The braid is not a power supply connection.

I know, it has a separate negative wire, which is connected to the braid and to the cars ground, which is what I connected my negative too