Won't go into 4 wheel low or 4 wheel hi

The actuator could be bad and not telling the motor to switch, or it could be the switch.

have the actuator (mounted on the drivers side transfer case) checked. that is what makes the selection from 2-4 hi-4 low. it takes the place of a gear shift. they are a fairly inexpensive and easy repair (if thats the problem). i would start there providing you have checked the fuses and relays. i hope this helps.

I had a 4 wheel drive suburban..it had issues with the high-lock and low-lock..I just used the auto setting because all four wheels were getting power anyway..only time you need lock is when you plan to go bogging in really deep mud..on snow/ice all you need is all wheel drive..you actually have better control..as long as it works in all wheel you should be fine..also be checking the front hubs.. are yours full time or do you have lock outs..on the axle hubs..thats my question

if its manual shift then inspect the linkage, if its push button then the motor/servo on the transfer case could be the issue. or the switch. i had to chase a simular issue on my tahoe and it ended up being the motor on the transfer case that selects the gears

Replace the dash switch.

it is most likely an automatic awd, 4 hi is full time 4 wheel drive, 4 lo is full time 4 wheel drive but at a very low gear ratio and should not exceed 25 mph or could cause damage. and DO NOT shift into 4 lo while vehicle is in motion. Auto is a 2 wheel drive but automatically engages into 4 wheel drive under heavy acceleration.

well, if you are sitting still it is recommended you put vehicle in neutral and select 4x4 indicator to desired posistion..... 4 high...4 low...or 2high (auto) when you select 4 low the top speed is not to exceed 25 mph. It is a very low gear for crawling or pulling. At any time you need 4 low gear you must stop trk, shift to neutral and select 4 low. The same procedure is done to change from 4 low to 4 hi or 2 hi. if not done this way internal trans, transfer case or driveline failure will occure. At any time you may shift 4x4 selector from (auto) or 2 hi to 4 hi, and 4 hi to 2 hi or( auto).****** But note, do not make shifts while tires are spinning or under power (acceleration)******* While driving you can make shifts at any speed between 2 hi (auto) and 4 hi and back to 2 hi. release throttle a little and select. you do not have to take foot off throttle all the way! just enough that truck is not under a power, load acceleration. If tires are spinning or you are on the gas and you select gears from 2 & 4 high the posibilities of severe damage can result. Also note that 4x4 is not recommended on dry pavement. When 4x4 is being used also take care as to the handling and the steering characteristics change, On tight turns the front wheels will bind and possibly **** a little. If you have never had a 4x4 before, obey what i have told you untill you get the experiance and you will be fine. HAPPY TRAILS.... AND A LITTLE 4X4 FUN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

did u try putting it in high low then putting the auto into reverse first then attempt to drive. had same problem with my truck

try selecting from nutreul or less then 3km

should have some kind of fault light on to read fault codes

its mostly an electronic solenoid shift system
could be a transfer box fault