4wd problem

[nestrong44]

I'm new here. I have an 03 Silverado with the NP8 autotrac transfer case. Sometimes when I start my truck even though the last time the truck was operated it was in 2wd the selector will read auto 4wd. Now today it was in 2wd and I went to put it in 4H and everything seemed normal. the switch operated correctly and once I hit the switch you can hear the encoder motor working. However once the vehicle appears to be in 4wd I never felt the front diff or hubs engaging and when I go to move the truck it acts as if still in 2wd. I also have a service 4wd indicator on the DIC. I swapped out the front axle actuator only to find out that did not correct the problem. does anyone think this could be a tccm issue or something else? thanks for the help.

[mike94silverado]

The inlaws o3 avalanche did tr same thing I'll have to ask them how they fixed it

 

 

Sent from my iPhone using Tapatalk

[nestrong44]

thanks let me know

[gmtech4]

scan it ,there IS a code in the TCCM ,,report back

[teacup]

have you checked the fuse? that's a good place to start,then check front actuator. I just had that problem and it was the front actuator, hope this helps.

[jdewolfe]

Sometimes the push buttons go bad and need to be replaced. Something with the soldering on them. My dad's 01 had that issue.

[nestrong44]

Ok so the switch is fine and the tccm is fine what I've done so far is before I replaced the tccm I couldn't hear the front diff actuator engaging now with the replacement tccm I can hear both the transfer case motor and the front diff actuator engaging so I thought maybe there was a problem in my transfer case itself because prior to all this I could hear some slack in the chain inside the transfer for like the past year. I put the truck up on four stands and tested 4wd with no load on it. Hey would you look at that 4wd works with no load on but once the weight of the truck is on the drivetrain well no such luck, any thoughts?

[sahls01gmc]

I have a very similar problem. I can get the front wheels to slightly turn when it is in the air, but they are no where near the same speed as the rear wheels.

 

Can anyone verify what fuses are associated with 4WD, and where they are all located?