For the 2005 and 1/2 model year VW Jetta, you will need a T-One Vehicle wiring harness, #118667, if you have the new body style. If you have the older body style, you will need the Hardwire Kit, # C59496.
Since the wiring on the harness and your Jetta is not rated for a charging application, you will need to hardwire a connector specifically for this function. You could use part # PK11851, mount it on your vehicle. Connect 6 gauge to 00 gauge wire from the positive battery terminal... view full answer...
The trailer hitch I recommend for a 2005 Volkswagen Jetta New Body is the Curt Trailer Hitch Receiver part # C11474. It has a class I rating with 1-1/4" receiver tube opening. Then for the trailer wiring harness, I recommend the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118667 which has a standard 4-way flat connector. view full answer...