Honda TRX420TM Owner's Manual page 205

If a Fuse Blows
If you do not have a spare fuse and you cannot ride the ATV without
fixing the problem, take a fuse of the same rating or a lower rating from
one of the other circuits that you can do without temporarily.
If you replace a blown fuse with a spare fuse that has a lower rating,
replace the fuse with the correct rating as soon as you can. Also
remember to replace any spare fuses that were installed.
If the replacement fuse of the same rating burns out in a short time,
there is probably a serious electrical problem on your ATV. Leave the
blown fuse in that circuit and have your ATV checked by your Honda
dealer.
Taking Care of the Unexpected
195