2005 GMC Envoy Locked in 4WD all the time

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did you turn the locks on the wheels, or check the fuses

You can't use 4 wheel on dry or even wet pavement. It must be snow dirt gravel or mud. Pavement will just burn up your tires because the front Axel pulls faster than the rear. When you have good grip there is a friction fight between front and rear tires.

never use 4wd on dry pavement even just wet pavement can cause this. 4wd is for only snowy or slippery conditions

unless this is automatic 4wd or awd than u have a problem id suggest you find a forum for youre vehicle and post it there find one by googleing gmc envoy forums or chevy trailblazer forums as they are the same thing

Check fuse #48 in the rear fuse panel first. If fuse is good, you may have a bad selector switch or the TCCM (Transfer Case Control Module) has gone bad. A technician with a high end scan tool can diagnose the system.

The Hummer H2 and H3 are both all time 4WD. There is no way to put it in 2WD. Now, you can select 4WD High or 4WD Low. You can also, if your vehicle is equipped with it, lock the front or rear wheels through the differential selector. This is one of the primary reasons Hummers get terrible gas mileage is because they are always in 4WD.
The only other solution is to swap the transmission to an Allison 6Spd, which is often done with diesel conversions, and they usually give you a 2WD option, and can get up to 25 MPG out of an H2.......but that conversion is about $30k.

The basic explanation of these gears are as follows.
2up/2wd is a basic two wheel drive setting where the vehicle will react as a rear wheel drive. In this gear the transmission will only distribute power to the two rear wheels(best for all around driving with clear road conditions and will give the best fuel efficiency).
4up/4wd is a high speed four wheel drive setting. in this gear the transmission will always distribute power to all four wheels and will allow you to drive at higher rates of speed( good for poor road conditions when ice and wet roads are a moderate risk).
4dwn/4lo is a low gear four wheel drive setting where again the transmission will distribute power to all four wheels but will limit you to a low rate of speed(good for really rough roads and severe weather or very poor traction conditions).
auto gear selection is basically a all wheel drive setting, where the transmission will use a primary setting of rear wheel drive gearing until the vehicle slips or looses traction on one of the drive traction. as soon as the transmission detects a difference in wheel speed between the two rear wheels, at which time the transmission locks up the front differential turning itself into a four wheel drive, until the wheels have regained traction and remain spinning at the same speed for a set amount of time, at which time it will then unlock the front differential at return to a rear wheel drive setting. this is a good all around gear but will cause you to get slightly less mpg/kpg then a 2up/2wd gear would. i hope this helps

When you are finished with your 4 wheel drive,put the transmission in neutral, disengage 4 wheel drive and shift to reverse then back up a couple feet before shifting to forward gear.

need to check front differential out

Do you have the front hubs disengaged and the shift lever in 2wheel drive. If this is the case, the tyres will fight against each other while turning on bitumen.