Reversing sensors

[Tam67]

Hi all first time posting on this site I’m after some help.l have a ml 163 270 cdi 2002 I’ve owned it for 6 years.had all the usual problems so know it quite well. I reversed into a steel bollard and did some damage to my rear bumper I’ve got another one this has reversing sensors in it my question is what I need to get the sensors working I’ve found the connector for the wiring harness but that’s it any advice would be much appreciated thanks