Goldwing GL1800 Trailer Wire Harness Goldwing GL1800 Electronically Isolated Trailer Wire Harness comes with detailed instructions. Easy plug-in installation at bike end requires no wire cutting or splicing. The wire harness isolates the wiring between the motorcycle and the trailer to prevent electrical feedback into motorcycle. GL1800 Trailer Wiring Harness - Cyclemax GL1800 Trailer Wiring Harness (090-143T) Item: 090-143T Add-On (in stock) This is a trailer wiring harness. It plugs right into the factory wiring harness on all years of non ABS equipped Goldwing 1800's from 2001-2010. Honda GL1800 Rear Harness Grounds – Electrical Connection Mar 31, 2016Honda GL1800 Rear Harness Grounds As any motorcycle ages, design defects begin to show. Things the manufacturer can’t simulate in a few years of testing. One of those are 2 ground wires on the GL1800.