Howdy and welcome from Northern Iowa
.
First guess would be neutral safety switch, or shift control motor. Read this thread
I have a 2018 1000/5 with very low, light duty miles and now it won't shift out of first. The "1" is blinking a 5 long and 2 short code but I haven't been able to find what that indicates anywhere. I changed the oil last summer and everything still looks good there. I did a clutch relearn but...
www.hondapioneerforum.com
Look for chewed wires.
.
And then, this thread has all of our COMMON Honda problems read through it.
I am having similar issues as a few others who have posted. This past week I took out the 2016 Pioneer 1000-5 and it was bucking as struggling to stay running when I put it into gear. It acted like it was set too low of an idle and/or was being starved of fuel. After about 5 or 6 re-starts...
www.hondapioneerforum.com
.
Here is a service manual I found online, hopefully it is still up and available.
Get it before it disappears like the other one.
www.dropbox.com
.
That should be enough to keep you busy for awhile.
.
Hopefully you will post back what you find, and how you fixed it.
Maybe it will help someone else.
.
Have a good day
