Will not shift into 4HI

Put truck in Neutral while key in run position engine off or on (doesn't matter which). If it's pushbutton 4wd then try hitting 4low again. if that doesn't work some of the chevy trucks required you to press 4hi to get into 4high and then press 4hi again to get back to 2hi, unless yours has a 2hi button. In that case press 4hi to get into 4high and then press 2hi to get back to 2wd. either way you need to be in neutral to get out of 4lo. I have shift on the fly (Mechanical Shifter on floorboard for transfer case) on my 1990 Suburban and still have to put it in neutral to get out of 4lo. Good Luck.

You have to put the truck in neutral first then switch the 4hi and don't use the auto select. If it still won't switch you may have damaged the servo and need to replace it. Or worse damaged the transfer case. So try in neutral first and hope that works.

Disconnect the battery for 30 minutes and try again. Be sure to follow the correct procedure for shifting from 4lo to 4hi or 2wd. That would be: engine running, transmission in neutral, foot on brake, shift to 4hi or 2wd. If it is a push button shift, hold the shift button in for a few seconds. If you hear the shift motor actuate, put the transmission in reverse and back up a few feet. If that does not work you may have a bad shift motor.

Shot in the dark but I have done this before! Back up at least 50 yards in reverse with the selector set to 4wd Lo come to a stop, put your transmission in neutral, shift the 4wd selector to 4wd hi wait for a few seconds, shift it to 2wd hi wait a few seconds then put your tranny back into drive and see if that takes it out of 4wd. Good luck

ok what i would try is put the truck in park then try to **** into your 4wheel drive high or low, other than that with the computer thats on board you may just have a technical issue that can be solved at the dealership

Change shift solenoid

try reverse and push the button

ithink it might be just a bad senser

Most common problem is the vacuum diaphragm that is so inconviently mounted UNDER the battery tray.The cable that locks in the front diff is attached to it and vacuum pulls it in/out.

try resetting the 4X4 module first. Remove the courtesy lamp and ATC fuses for at least 1 minute the reinstall fuses. Cycle key on and off 5 times then try your four wheel. Please rate if this works.