2004 F150 4X4. There's a thin cable from ? to my left rear wheel that is broken in to (apparently snagged on something?). What is that called and how do I replace it? ABS light is on, so I'm assuming it has something to do with the ABS system. Thanks.

 

Sounds like a wheel speed sensor.

 

it could also be a parking brake cable...
which would be unrelated to the ABS light on

when you say "cable" do you mean braided steel or do you mean wires?

 

DUH! I saw cable and didn't see the OP said rear wheel. I believe the abs sensor (speed sensor) is in the diff at the rear.

Still could be if it's electric cable. If it's a steel cable then mkosu04 is right.