http://www.grizzlycentral.com/forum...501parts-com/48506-updated-4wd-testing-repair-step-step-videos-parts-links.html
If your 4wd is going in and out without pressing the button, it is something that you can fix fairly easy. This is actually a common problem with the 12-15 models. Most of the time, the problem boils down to an intermittent connection. After dealing with this on several occasions, I have found a few things that will fix the issue.
Step 1- Pull the plug off of your servo that’s on the front diff and put a dab of dielectric grease on the contacts and plug it back in. Ensure the connection is tight. Do the same thing to your plug coming from the 4wd switch. This usually fixes the problem. It also doesn’t hurt to apply dielectric grease to the 4wd relays while you’re at it. If you’re still having the problem, proceed to step 2.
Step 2- If you’re still having problems after doing the previous step, remove the switch, clean the contacts inside and reassemble. You can see a video here on how to do so.
If you are still having problems after doing this, you could possibly have a broken or shorted wire somewhere between the switch, relays, and servo. Give the wiring a good once over inspection and see if you can see any obvious problems. Let us know if we can help you further.