Will only switch out of 2wd in neutral

[WestCoastie]

Maybe I'm not understanding your post but you're supposed to be in N when you change to 4H ,4L, and back to 2H. As for Auto, the only time I used it, I engaged it while climbing a hill then I lost my front diff. The fork got bent I assume it's because I was moving while it kicked in. I know, it's Auto, it should work automatically! Needless to say I'll never use Auto again.

Right, I don’t exactly have a problem swapping into 4HI and 4LO and back to 2wd. As you said that part is working properly. But shifting into 4Auto I shouldn’t have to be in neutral, but that’s the only way I can get it to work now.

I used to have an 01’ 2500 with the 6.0 and it had 4Auto. It worked flawlessly and I never had a problem. The Yukon use to work fine, just decided to stop doing that I guess.

 

[Fless]

Maybe I'm not understanding your post but you're supposed to be in N when you change to 4H ,4L, and back to 2H. As for Auto, the only time I used it, I engaged it while climbing a hill then I lost my front diff. The fork got bent I assume it's because I was moving while it kicked in. I know, it's Auto, it should work automatically! Needless to say I'll never use Auto again.

Not on the later transfer cases like the OP has. This is an '03 and the only time he should need to have the tranny in neutral to change modes is to go in and out of 4LO. Every other mode change is on the fly.

 

[Fless]

Thank you, I’ll try and get those codes checked and cleared. Will a regular OBD2 scanner work or do I need one of those fancier ones

All those grounds are good except the one in dash I have not checked. Is there anywhere to see more graphics like the one you sent? The zone map is helpful in pointing to the area but doesn’t specify exactly where the grounds are. I think I’m just going to try and clean them all up if I can.

Tomorrow I can definitely get the switch swapped out. I’ll let you know if that does it.

You'll need a bit more advanced code reader; the typical scanner won't read those codes. Sometimes the auto parts stores will have one of those to use.

 

[B-train]

Thank you, I’ll try and get those codes checked and cleared.

All those grounds are good except the one in dash I have not checked. I’ll try it as well.

Also, all 4 tires and wheels are the same size, but front aren’t damn near bald and rear almost new. Couldn’t be helped, just how it worked out. Should be fixing that soon.

Got burned as a young tech for a K2500 that wouldn't shift out of 4wd except for when in neutral. It was warranty and I went through the whole TC (did find some worn parts from binding). Put it back in and thought I had it, but then it acted up the same way.

Called a buddy of mine who is a master GM tech for 35 years and he asked about tires. I was a little confused at first but told him the size and condition- same as yours. He said swap one side front to back. Viola!

Worked perfectly, I felt dumb, but learned a good lesson that has never left me. I encourage you to give that a try and see. Then get a new matched set of tires and keep them rotated.

 

[WestCoastie]

Got burned as a young tech for a K2500 that wouldn't shift out of 4wd except for when in neutral. It was warranty and I went through the whole TC (did find some worn parts from binding). Put it back in and thought I had it, but then it acted up the same way.

Called a buddy of mine who is a master GM tech for 35 years and he asked about tires. I was a little confused at first but told him the size and condition- same as yours. He said swap one side front to back. Viola!

Worked perfectly, I felt dumb, but learned a good lesson that has never left me. I encourage you to give that a try and see. Then get a new matched set of tires and keep them rotated.

Never would have thought that would matter that much. So basically just swap front for back?

Also, tires are only that way because when I bought it front had a little life left, and rear were completely bald. Didn’t have money at the time for all 4 and I hate the stock rims, so I planned on doing everything when I could get new wheels. Skip to now when I get new wheels and figure out they are lug centric… now I have to get an adapter… then all new tires

 

[B-train]

Never would have thought that would matter that much. So basically just swap front for back?

Also, tires are only that way because when I bought it front had a little life left, and rear were completely bald. Didn’t have money at the time for all 4 and I hate the stock rims, so I planned on doing everything when I could get new wheels. Skip to now when I get new wheels and figure out they are lug centric… now I have to get an adapter… then all new tires

Just switch one side of the truck front to back. This will allow the rolling circumference differences to be equalled out by the open diffs.

With different circumference tires, one set will be covering more ground than the other 2 and then they fight each other when locked in 4wd. It's either trying to stretch your truck, or accordion it depending on the situation. LOL

 

[WestCoastie]

Just switch one side of the truck front to back. This will allow the rolling circumference differences to be equalled out by the open diffs.

With different circumference tires, one set will be covering more ground than the other 2 and then they fight each other when locked in 4wd. It's either trying to stretch your truck, or accordion it depending on the situation. LOL

Ok, I’ll get there when I can. Tried swapping out the switch and it made no difference, but that’s easier than swapping tires around.

When I did get it to swap into 4Auto it really sounds like it’s binding up. Not sure if that’s because of the tires, it needs oil in that front diff or something else.

I’ll report back as I try things. Thanks again

 

[rockola1971]

Ok, I’ll get there when I can. Tried swapping out the switch and it made no difference, but that’s easier than swapping tires around.

When I did get it to swap into 4Auto it really sounds like it’s binding up. Not sure if that’s because of the tires, it needs oil in that front diff or something else.

I’ll report back as I try things. Thanks again

If you are in Auto 4WD the Tcase should not physically be in 4wd UNTIL there is a wheel speed difference detected via the front/rear driveshaft speed sensors which means you have wheel slippage. So if you are actually in AUTO 4wd and the Tcase is in 4wd (which means the clutches are engaged within the Tcase in the Auto section) then you have an internal problem within the Tcase OR the computer is getting false information from the driveshaft sensors that you have wheel slippage. See the attached NP246 Tcase writeup. I believe you are getting false information to the Tcase because in order for the vehicle to be truly in 4wd from Tcase to the front wheels the front axles have to be engaged and that would need an active command for 4wd UNLESS you have 2 faults happening and your front axles are engaged at the front diff because of a mechanical failure at the actuator.

 

[WestCoastie]

If you are in Auto 4WD the Tcase should not physically be in 4wd UNTIL there is a wheel speed difference detected via the front/rear driveshaft speed sensors which means you have wheel slippage. So if you are actually in AUTO 4wd and the Tcase is in 4wd (which means the clutches are engaged within the Tcase in the Auto section) then you have an internal problem within the Tcase OR the computer is getting false information from the driveshaft sensors that you have wheel slippage. See the attached NP246 Tcase writeup. I believe you are getting false information to the Tcase because in order for the vehicle to be truly in 4wd from Tcase to the front wheels the front axles have to be engaged and that would need an active command for 4wd UNLESS you have 2 faults happening and your front axles are engaged at the front diff because of a mechanical failure at the actuator.

We’ll I woke up this morning and the lights on the 4x4 switch were out and message center immediately said service 4x4. Soo looks like it’s electrical? I still haven’t found anywhere that has a code reader fancy enough to read tranny codes.