Will not switch into 4 wheel drive - 2002 Chevrolet TrailBlazer

There are several possibilities. If you have a 4x4, the unit could be between the 2 wheel drive and 4 wheel drive modes. There is also a 4 wheel drive low and 4 wheel drive high mode. On some models the selector switch is similar in appearance to the blower motor selector switch. Someone could reach for the blower speed and turn the 4 wheel switch instead.

Another possibility can be a burned out led indicator switch on models which use electric shift solenoids to position the drivetrain between 2 and 4 wheel drive. The voltage gets messed up because of the burned out bulb and the shift plunger does not go into the correct position.

Have your error message read by a scanner.

I really don't know quite how to tell you this. Everything seems to be working just fine buy your question. When your using 4 wheel drive, you engage the hubs first, then push the 4 wheel drive button or turn the switch. Ease it in and out of gear or shift on the move and you should be in 4 wheel drive at this point. To take it out of 4 wheel drive, reverse this procedure. Turn the switch off and ease forward and you will be out of 4 wheel drive. If your not going to use your 4x4, turn the hubs out to reduce ware on the axles. If you will be using 4x4 again soon, leave the hubs in and all you have to do is turn the switch to 4x4 and your set to go. I hope I explained this well enough. Good luck.

It sounds like a welded contact.

Call the dealer.

More than likely it is the switch alot of electric 4-wheel drive switches have been known to go bad from lack of use

Most alignment shops these days use a 4 wheel system,so they see all 4 wheels anyway,I would try to tell the shop if the rear is ok ,just do the front.
That 2 wheel 4 wheel price is a moneymaker
So hard to find an honest shop.

check switch first ,by pass it and see if problem ceases

check fuse and relay to switch if power to switch retest switch new doesnt mean not defective if no power check connections and wiring for damage or breaks

Have you checked the switch on the transfer case? Those switches tend to go bad and primarily operated the 4 wheel Hi.

this switch does not switch the vehicle from 2 wheel to 4 wheel drive. Grand cherokee have a manual shifter for that. The 4x4 switch is on top of the transfer case and tells the driver information display what 4 wheel drive mode the Jeep is in. ex..if you have selectrac, in 2 wheel the rear wheels on the display will light up, in 4 wheel all 4 wheels will light up, in 4 wheel low it will have the word low lit up in yellow. This is the only purpose for this switch and a bad one will not affect the functioning of the 4 wheel drive. Check out Rockauto.com and a new one can be purchased for about 35 dollars. If you call the dealership and ask for a 4 wheel drive switch, they will have no clue what you are talking about. The actual name is " 4WD indicator light switch"