Welcome to the site !!
The Voyager is a slightly different animal to the KZ when it comes to the electronics side of things. The best I can suggest at this point is to download the service manual for the Voyager from the "Service Manual " Tab of this site and on page 35 of 142 you'll find the wiring diagram. it should be easy enough to follow.
One thing that all of these bikes seem to suffer from is grounds. We keep running across electrical issues and quite often, there's a ground wire problem.
Another issue than can crop up is wiring that "looks" ok but there's high resistance at the terminal ends on the wires.
Then there's always my favorite. Punctures through the wiring pvc sheath. Some guys like to search wiring issues with probes with needle point ends and they like to puncture through the wiring to check for voltage part way down the wire. Years later, corrosion happens at the puncture points and then there's an open circuit in the wire or high resistance. Bad practice and people should be spanked for doing it.
You can always check back with us and we'll attempt to help. Last resort there's a site specifically for the Kawasaki Voyagers (both the 1200's and the zn1300's ) called American Voyager Association. I will tell you that there's a membership cost on that site.
For the most part, the ZN1300 is a KZ1300 until you get into the electronics side of things.
Hang in there. Your problem should be a simple fix. Let us know how you're making out and if we can help.
A here's a big tip that I've suggested to all our members. Take a copy of the PDF file of the Service Manual to your local print shop and have them blow up /print the wiring diagram page on 11" x17" paper and them have them laminate the print. It should cost you less than $10.
When you go to trace a wiring diagram you can use a waterborne marker and mark up the wiring diagram as you go through your tracing of the circuit. After you've finished your work, you can erase the mark ups and hang the diagram up on the wall as wall art for your shop and you'll have it for the next time you need to trace a circuit. It's much easier to follow on the larger paper size.
KB