4 Auto Works, 4 Low Works, 2 High Works, But 4 High Doesnt..

[robbd]

This winter I was working up north on some pretty adventurous terrain to say the least and when I put my truck into 4 High as the manual explains to, I got nothing. It didnt work but there was no time to check it out as I was heading to my work camp. I put it in 4 Low and made it to camp fine with 4 Low working fine. Since then I've tried using it again and still nothing. My 4 Auto, and 4 Low work, but I have yet to been able to get 4 high to work.. Any Idea's or suggestions? (Its a 99 Sierra 1500 z71 4x4 with the 5.3L)

 

- I would take it to the dealership to get it checked out but the last time I did that they tried feeding me so much bullshit about needing a $4200 fix of things that were either not broken, or unnecessary that I dont plan on goign back to them, I just moved here and dont really have myself a good mechanic who I can actually trust the slightest.. so any help would do me great..

[pwall]

If the 'Auto 4WD' is working, you do mean that the light comes on when you push the button, or do you actually feel something engaging?

Auto 4WD will put your truck into 4HIGH when required. So, if that does work, it might just be a switch problem with the 4HIGH.

[robbd]

Yeah 4 Auto Definatly engages cause our work lease was knee deep mud and i was spinning in 2 and I had my boss out to tell me if anything was spinning in the front and when I put it in 4 Auto it was gripping all 4 and as a result I got through it. A switch? like are you meaning the button on the dash ?

[Wires]

This winter I was working up north on some pretty adventurous terrain to say the least and when I put my truck into 4 High as the manual explains to, I got nothing. It didnt work but there was no time to check it out as I was heading to my work camp. I put it in 4 Low and made it to camp fine with 4 Low working fine. Since then I've tried using it again and still nothing. My 4 Auto, and 4 Low work, but I have yet to been able to get 4 high to work.. Any Idea's or suggestions? (Its a 99 Sierra 1500 z71 4x4 with the 5.3L)

 

- I would take it to the dealership to get it checked out but the last time I did that they tried feeding me so much bullshit about needing a $4200 fix of things that were either not broken, or unnecessary that I dont plan on goign back to them, I just moved here and dont really have myself a good mechanic who I can actually trust the slightest.. so any help would do me great..

 

My guess is the dash switch is the problem. My '00 had issues, and I just pulled the switch out, resoldered the connections (was a TSB on bad connections or somethign like that). Fixed the problem. Like the post above, if it works in auto, then the t-case is shifting properly, and it's something minor in the electrical.