I purchased a Kenwood KDC-BT838U and it supports USB.

Kenwood - KDC-BT838U

The problem is that the USB cable on the Fit seems to use a proprietary connector that connects to the stock headunit.

Does anyone know how I can connect the Fit's USB cable to the back of the Kenwood, which uses a standard USB port?

 

you might have to purchase the cable that is specific to the kenwoods.
the oem cable is weird. it attaches to a box under the radio.
i don't think your kenwood can hook up to that.

 

For my Pioneer, I just pulled the standard Fit cable out of the glove box and ran the Pioneer one through the existing hole. It's not noticable (and it's inside the glove box anyway). If you're obsessive, you could probably cut the grommit/mount off of the original cable and glue it around the new one to make a perfect fit. I used zipties to attach the cable to nearby structure under the dash so it wouldn't flop around.

 

I worked at Best Buy installing head units for a few years or so... The Fit's cable isnt compatable with the Kenwoods. The kenwoods end of the cable is a circle and the fits is kinda square looking. The only way to connect the Kenwood is ordering it through kenwood. BUT, if you look on ebay its like $20 for that cable. Just make sure its a kenwood brand cable, dont buy the cheaper cable. Its going to short out quicker when you bend it. Hope that helps. Good luck!

 

Here's how to do what SteveInNC suggests. The stock USB cable enters the upper glovebox via a removable panel. To pull this panel out, open the lower glovebox as you would to change the cabin air filter and reach up to the right outside of the upper glovebox. It's tight, but you can feel two of the clips that hold the USB panel in--press on these with some force until you can pry the whole panel loose. Once it's out you'll see that the cable itself threads through via a small block of rubber, which itself can be removed from the panel. Do so, and then tuck the stock USB cable back into the dash in case you need it at some point in the future (perhaps they'll come up with an adapter that let's us connect the stock USB to a 3rd-party unit). This leaves a 1/2" square hole in the panel, through which you can thread the new USB cable. Once you've done this, snap the panel back into place and you've got an installation that's almost as clean as the stock.

 

cut a normal usb cable in half. Cut the fit cable in half. Splice wires. Tell us if it works.