I installed a factory nav radio into my 2012 impala. The instructions call for it to be tied into the Vehicle Speed Sensor wire. Everything on the radio works except the turn by turn directions which apparently tapping into that wire corrects. The wire is supposed to on a harness that connects to the EBCM. I was lucky enough to have a GM tech I know print me the wiring diagram for the harness. I then had my car audio guys go to tap into it and it wasn't there! They pinned out the entire harness and every single wire was there as it should be except for the VSS wire. Please help! I'd really love to have the turn by turn working on this radio.