My brother-in-law has a 05 450 kodiak with diff lock which will not disengage.We tested every wire and we could jump the wires so we could hear the motor engaging but when reversing the connection,nothing. There was no broken wires or no shorts.He has the wiring schematic from yamaha so we checked every circuit that we could.We think now that it may be CDI related, but the bike runs very smooth and starts in a split second. Any input would be greatly appreciated.
THANKS IN ADVANCE

 

It won't disengage at all? sometimes I have to press the button and back-up for it to unlock.. Try that !

 

He has tried all those little tricks! Nothing seems to work. The bike hasn't disengaged at all since this happened{about 3 months ago}. You can still ride it but it's hard to steer and it doesn't get it's speed up.

 

possibly a bad servo motor

 

Try putting it's wheels up off the ground. Then try different things, wheels moving, not moving, forwards, backwards and see if that makes a difference.