Constant tone coming From Car, What is this box?

[Syecadelic]

Hey guys

 

have a technical issue which has just arrisen.

After wiring my door speakers into a new amplifier, when i put the key in the ignition i get a loud constant tone.

 

I have traced it back behind the passenger side of the dash (UK CAR)

 

The white box pictured below seems to be the source. when i disconnect the lower plug the tone stops.

 

My tail gate/ trunk / boot hatch motor doesnt seem to operate at all off the unlock button on the drivers door pannel

or indeed the boot release on the bumper.

 

Any idea what is going on ://

 

it done this tone before when i hard wired the speakers to the headunit but then somehow stopped.

 

Any help would be appreciated