The earth on these looms seems to corrode leading to back-feeding of voltage and bizzarre lighting behaviour and sometimes odd speedo movement.
You can fix the looms if you are keen and know how to track down the dud connections (caused by corrosion where wire joins metal frame) by testing resistance (continuity) from each pin on the plug to it's end point at the other end of the wire (not just at the end of the wire but at the piece it connects onto) Once you have located the duds mark them then you need to solder the wire onto the metal frame, re-doing the standard connector will not last long. The metal frame will not come out of the plastic holder easily you will need to apply an electric drill to get it out.
Sorting these looms will fix most lighting issues you will ever have on a VN-VP. It's worth sorting out, once you've done one side the next one will take about 15 minutes.
With the looms and plugs out you can also see exactly how the single and double filament bulbs go in and which way around the double filament bulb goes
(hint park light filament is less bright than brake light filament)
You will need a multimeter or a test light and 12 volt battery charger to find the bad connections. I prefer to use a multimeter.
Enjoy!
PS you can buy these looms new from Rare Spares for about $30 each.
Just a question Warranty, what makes you think back feeding is happening on a DC circuit?
The most I could see occurring is the corroded base for the globes bridging the brake or parker circuit, and one or more globes are feeding from a single or multiple bridged positive? remembering they are all positively switched, and all share a common earth.
I ask this because back feeding refers to reverse polarity in a circuit (usually from induced current) and I work in the industry.
So i'm not having a c0ck measuring contest with you, i'm asking where your coming from because maybe there is something i've missed or haven't thought of....
Cheers