Remove the R4 connector from the back of the radio. The photo shows what you'll see laying on the floor of the car in the drivers well, with your head near the gas pedal, looking up near the area where you removed the box in the previous step. The R4 connector is the one furthest towards the passenger side, plugged in to the radio which is the part with the bare metal with all of the holes in it. There is a button on the top side of the connector that you must press before you can pull the connector out. Pull on the plastic body of the connector, not the wires. The connector is identical to one on the Y cable that comes with the kit, so examine the connector on the Y cable to familiarize yourself with the button operation. You can also get easier access to this connector by dropping down the glove box (how to do this is described in the owners manual for changing the interior air filter). It's difficult to see what you're doing this way, but you will have more freedom of movement and be in a more comfortable position.