Whenever i try 2 shift into 4hi, both the 4hi/4lo lights blink a few times until it just goes back to 2hi. That reaction only happens in neutral. no reaction while in drive. 4lo does engage in neutral but not 4hi. please help,, what can i do.

I had this problem, and I did the unhook the battery trick. Just unhook the positive on the battery for about 15 minutes, and then hook it back up. It must reset the computer. I did this, and haven't had a problem since. Good luck.

If that doesn't work, your vacumm actuator is probably defective.