Freelander 1 Intermittent PDC System Fault

For the last few months the PDC system on my 2005 FL1 has been playing up. After driving in pretty wet weather it will error. Then after a week of so of dry weather it works again, until the next moderately wet drive. All the sensors are clicking all the time, and whilst I have a known working PDC module in my spares box I suspect a dodgy connection or water ingress somewhere on the underside of the car. I can't seem to find any info on RAVE for the wiring etc so I was wondering if anyone has any pointers on locations of earth points or wiring connections I could check before swapping the module? I'd also like to avoid having to take the bumper off if poss but suspect that this is probably necessary to get a visual on the sensor connectors?

Do you have a suitable device?
I'm sure my Delphi clone reads the PDC module, although I could be mistaken.
From memory, the ground points are local to the module, which is mounted near the RH right hand strut top. The harness for the sensors goes through the boot floor, RHS, behind the trim panel.
Access to the sensors is best achieved by removing the rear bumper, which doesn't take long, once the rusted screws are removed. I replaced all mine with stainless steel, to prevent future issues. I've just ordered some stainless screws for my own FL2 rear bumper, which needs removing so I can fit my newly acquired tow bar.

Cheers Nodge. I need to pay you a visit sometime soon I think. Get that bathroom sorted!

As it happens, a warm dry day today saw the sensors burst into life again this afternoon.