QVHK

I have sourced a complete set of external temperature sensor-***-display unit, and would like some advice on the wiring connections. I attach a photo of the unit showing the power cable (A), the temperature sensor (B), Cable (C) in red-black, and Cable (D) in black. I understand that Cable A should draw power from the instrument cluster - there is only one connector that fits, but it is already taken. As for B the temperature sensor, it should go under the front bumper. As for C and D, one of them should play as ground but I do not know which one, and where to affix them. Would appreciate some help.