I'm attempting to replace the stock unit with a JVC head unit in order to have phone access. The plug has me confused. The harness I purchased was supposed to be for my 2007 Ram 1500. The speaker wiring seems to be OK, but there are two yellow wires on the harness that connect with two grey and red wires on the factory plug and there is no connection to the red wire on the aftermarket harness. When I do connect these and the ground, the 20A fuse blows The really odd thing is that both grey/red wires measure 6 volts . Does anyone have a pin-out for the factory radio conn?