Honda ES Electric Shift ATVs have common failures in the gear shift system.
If you look at the various forums, and read a lot of posts, the problem can be the computer (ECU),
or a sensor (angle sensor, gear position sensor, speed sensor), or a break in the wiring,
or the shift motor, or broken parts in the shift motor gear linkage.
Replacing parts one after another can be very expensive (about $1000 for Honda parts).
First check that the shift motor works with a jumper to the battery (quick touch only).
Then, to save a lot of time and money, bypass the electronics all together with my $50 relay system .
This work around fixes problems with broken ECU/Angle Sensor/Speed Sensor/Wiring Harness/etc.
(NOTE - Shift Motor must be functional, and manual gear change tool must work).
Honda designs ATVs very well, but the ES system is a weak link. Their design uses an angle sensor
to detect gear shift process completion so the ECU will then stop the shift motor voltage.
Problems can occur when there is a gear jam which stops the gear shift from completing.
Broken parts can be caused by holding the shift button down too long while there is a gear jam.
That is why I have an optional timer circuit to only allow voltage for a quarter second (add $40).
Adding a timer will improve tha ES system reliability. It adds an extra failsafe layer.
Money back guarantee. If it doesn't work, send it back.
Shift Buttons Work Perfectly after installing relay system
(note - the lower button box is for my winch).