Bought a pioneer single DIN and the rp4-ch11 PAC wiring harness to allow for steering wheel controls. Steering controls work, but the only speakers that make sound are the factory sub's in the doors. There is an extra square (8 pin?) plug coming from the truck that has no where to plug into this new harness. Is there splicing necessary? Wrong harness or additional connector needed? I think best buy set me up with the right stuff but who knows...