it is the wiring harness that run from left to right headlamp under the radiator/condensor/fan. It is the plug in between the air bag sensor wires.
what is the plug for at the bottom of the h.lamp wiring harness under the rad? on 2008 Chevrolet Impala
Maybe it is for your fog lamps (or what would be the fog lamps if that option isn't on the vehicle. Give me the last 8 of the vin and I can research it for you.