4x4 Trouble

[tennessee98]

I have a 08 Sierra with the 4x4 shifter on the floor. When I try to shift to 4hi from 2wd, it won't let me 90% of the time. It will always let my put it in 4hi if I am at a complete stop. And other times it is hit or miss. We just got snow where I live on Sunday, so that is when I noticed this problem. Any ideas what it could be?

[oldmann]

Could be snow wedged up under the truck twisting something. Just roll slowly when moving the lever into 4*4 if you can. Stopping with the brakes just binds things up sometimes. Stop, then let off the brake a bit, then shift in or out.

[tennessee98]

Could be snow wedged up under the truck twisting something. Just roll slowly when moving the lever into 4*4 if you can. Stopping with the brakes just binds things up sometimes. Stop, then let off the brake a bit, then shift in or out.

 

 

I will try that. I was wondering if it could be the linkage. Either way, it goes in Friday to the dealership. The factory warranty expires in 12 days on 12/26/10, so I'm not gonna mess around.

[nickvrebel]

on the floor shift transfer cases usually as long as you don't bind them up they shift pretty easy. Just don't have your foot buried in the accelerator when you are trying to shift, but at least have a slow roll (not a complete stop)... you should be able to easily make the shifts even at highway speeds.

[ColoradoSkiCountry]

What Nick said. The same applies to those with the Auto-Trac Transfer Case with those push buttons or that stupid knob. (Give me a floor transfer case shifter anyday)

[ChevyTech77]

Mine bound up last night a bit on the first shift from 2HI to 4HI but it has also been sitting half barried in a

snow bank with negative overnight temps so I figured there was just something cold and stiff holding it up.

After the first shift, it is breezing back and forth like normal now.

[tennessee98]

Update on this situation. The GMC dealer was able to get my truck in today instead of tomorrow. They gave me a copy of the bulletin Gm released on 9-16-09.

 

Here is the base of the statement...

 

CONDITION - Some customers may comment about the effort required to shift from 2HI to 4HI in cold ambient temperatures at 20 degrees F.

 

 

CAUSE - This condition may be caused by the standard front axle being equipped with conventinal mineral oil axle fluid. In cold temperatures, prior to complete warm up, the fluid viscosity is thick. This may affect transfer case shift performance prior to full warm up.

 

CORRECTION - Drain the front axle fluid and refill with GM SAE 75W-90 Synthetic Axle Fluid, P/N 89021677. Refer to Front Axle Lubricant Replacement in SI. It is important to use synthetic fluid in this 8.25" axle to improve the performance of the 4WD sysetm in cold ambient temperatures.

 

 

 

 

This is the steps the GMC dealer took today on my truck. The 4WD shifted fine after I picked it up this afternoon. But as I stated to the guy in the service department, my problem was ongiong, after my truck was fully warm, just not while it was cold. I guess I will see how this synthetic axle fluid works. Hope that is all it needed, but I have a feeling I may be back in the service department soon.