97 jimmy 4wd

[lurchy98]

I have just purchased a 97 jimmy with the push button four wheel drive. My problem is that it will go into 4 lo but has a hard time going into 4 hi. I have tried to put it in 4 hi several times and have only been successful once, it will just blink then go back to 2 hi. So is there a problem or am I doing something wrong. Any info you have will be greatly appreciated. Thanks.