Finally got round to fixing the cracked insulation on the wires in the grommet to the boot lid. I knew they were cracked and had temporarily wrapped the bare wires in loom tape to prevent any shorts, but my reversing camera stopped working so I thought it was time to tackle the job properly. 5 wires in the main loom were visibly cracked and the cause of the reversing camera failure was that 4 of the 5 wires, excluding the coax for the video feed, were broken.
This really is a crap design. The bend radius when the boot is shut is far too tight, failure is inevitable with the type of wire they have used. The OEM reversing camera wires are very thin, there would be relatively little time between the insulation cracking and copper core breaking.
I decided that I might as well do all the wires and replace the section inside the grommet with silicone coated wire which is much more flexible and resistant to fatigue. I also thought it best to replace the boot grommet as I certainly don;t plan on taking all the wires out again!! The inside of the old grommet was coated in old loom tape glue, horrible stuff that seems to be almost impossible to remove. After stripping the wire from the boot lid and removing the grommet from the body, I cut all the wires at about the point they enter the grommet. As I didn't have 20 different coloured wires (why the hell do you need 20 wires going into the boot, including the 5 for the camera and 2 for the coax for the video feed?) only 4 colours, I labelled all the wires as I extended them with the silicone wire and finally soldered them to the original loom together with heat shrink tubing over the joint.
Before threading the loom back into the boot I wired it all up to make sure it was working. Everything worked perfectly so I threaded it back into the boot. I had anticipated that fitting the grommet back into the body as it's double skinned would be quite hard, but actually it was pretty easy, inserting it up from the inside. The bit that took the time was preparing, soldering and insulating 40 joints in the wires, especially the 20 joints that had to be made in situ in the boot.
As soldering wires together inside the confines of the boot is not easy I wrapped each joint in a small piece of loom tape just in case there was a small solder spike that could penetrate the heat shrink.
The wires were then all bundled together with more loom tape and the boot trim re-assembled to finish the job, about 6 hours work in total. I do not want to have to do that again, and I've seen more than enough sticky black loom tape glue for the foreseeable future thanks.