Short summary:Restoration of '59 convertible - fit brand new wiring loom and rear off side lamp unit from well known parts supplier (late type). Car on road for three weeks in all weather conditions - day and night. Lights, heater and wipers on at same time regularly. All electrical systems operating fine no problems. Week on MMOC MOT 2013 no problems, everything working fine. Head to Switzerland/Italy for extra week of holiday and show at British Marques Car Show in Nantua, near Geneva - no problems. Head up Furka and Simplon passes - no problem. Descending Simplon Pass - lose brake lights and indicators. Fuse blown, replace fuse, check for any obvious issues, can't fix brake lights or indicators so decide to carry on and use tail lights as brake lights until I can stop to investigate issues. Ten/fifteen minutes later, lots of smoke in cabin and boot - wiring to rear lights fried and very small fire in boot which extinguishes very quickly. OK should have investigeted cause of original issues rather than carry on but hey! Car recovered back to UK. New loom needed and purchased. New loom fitted. All circuits seem OK but on testing lights rear o/s light very dim - thinks poor earth. Fiddle with wires and light goes brighter but now VERY hot and starting to melt. Circuit fuse does not blow - still intact. Switch off lights and disconnect battery - investigate wiring to rear light - now also melted and fused with other wires in the loom. Damage also to no. plate light wires and some evidence that wire to light switch is also damaged. New loom with power for no more than 2 minutes now toast
Investigate rear lamp unit as possible cause and upon releasing mounting bolts water begins to leak from inside the light unit - eventually about quarter of a small plastic cup of water emerges. Remove light unit - tide mark where water has sat since June covering earth connection and reaching to just below the stop/tail lamp bulb holder. Cause of water inlet likely to be the garages failure to properly block up unused mounting holes for new light unit (which, for some reason, didn't seem to fit the original holes). No damage at all to sub-loom taking power to n/s light unit which appeared to work OK. All three earth points in the boot are secure and contacting clean metal. All other circuits seemed to be working OK.OK question is - before I get to fit a third loom! Is the cause of the continual short and melting of the loom down solely to the water in the light unit creating problems or is it possible that it could be something else? Switch? Fuse Box? wary of blaming the smoking gun (or smoking light unit!!) and missing something else.
Before I fit a third loom I will run some wires from the switch and power source to light unit outside of the loom to replicate the rear lighting circuit to see if I can solve the problem but would welcome any thoughts from members as to other things that could have caused this issue.
Cheers
