03 grizzly 660 diff lock light stuck on.

There isn't one. You have to put one in-
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Grizzly 660 Shifting problem. - Yamaha Grizzly ATV Forum

www.grizzlycentral.com > ... > Grizzly Engine & TransmissionMar 12, 2012 - 4 posts This is a discussion on Grizzly 660 Shifting problem. within the Grizzly Engine ....2005 grizzly 660 gear position sensor problem.

Mostly this is caused by uneven tire ware , Jack up one wheel the wheel will spin half a turn or more as the transmission is under tension .you will now be able to move the selector.

change what isnt working one at a tiome..

Diff lock button is stuck,or broken ,most likely.

Yamaha Grizzly 660 2002 2008

get one of these..If you are going to try the repair yourself....
.this is serious, ....
there MIGHT be damaged components that need to be inspected by a professional.

Sounds like a faulty Diff Lock switch to me.
Most of the D2 models till late 03 model year use a version of firmware on the SLABS ECU that when diff-lock is detected puts the ABS and Traction Control systems into a lower response mode. Late model vehicles came with factory fit diff-lock linkages as a option, and the firmware was revised to allow this to operate in conjunction with the traction control.
Therefore ABS and TC illuminating (but with no HDC) means your TC/ABS is in the lower performing mode, and your diff-lock may be in, but more likely the £12 switch has broken, and needs replacing. It's a bugger of a job, and can be done from underneath the vehicle (did mine this way) the switch is p/no PRC2911, and just unscrews. It's located just behind the diff-lock stud above where the front prop fits.
Your options are thus:
1) Remove the front prop. Work blind and try and change it by feel alone. Helps if you can clean the area off before too, don't want any rubbish falling in the box! Unplug & Undo the switch, IIRC it's a 12mm head, and a stubby spanner is the tool for the job. Remove, swap the lower nut from the old switch to the new one (important for the length) and put back in. Don't do up too tight, or it may shear off (as my friend did 2 days after I did mine! He kept tightening it...) Pop the connections on and the front prop and the fault should go away. You could also just disconnect the switch if you want. IIRC open circuit is no-diff lock anyway, but if that's not correct then make up a link with some spade connectors and link it out then.
2) Remove the centre console, drill the rivets and attack from above. Same tools needed, just you can see what you're doing.
I favoured Option 1. YMMV!

I have one of these vans you can put it in 4x4 anytime while driving or stopped or taken out of 4x4. the diff lock does not have to be on to have 4x4 .this **** locks in the rear diff,giving you all 4 wheels,this diff **** should be pushed when stopped,and taken out when stopped,it is always taken out before the 4x4 is . ps the 4x4 light on the dash should not be blinking if it is your acuator is stuck it can be freed up for 30.00

Have you tried putting the ATV in reverse, drive 5 feet, then put in neutral and disengage the 4x4. I know that has worked with my 660. This has also worked with the diff lock.

not really sure what ur riding, but the bike u listed does not have a diff lock, due to the fact it has no differential????? u have a rear wheel, spokes, hub. brake systen & final drive sprocket...