Gm auto track transfer case question

[THEFERMANATOR]

Was the tccm programmed by the dealer? Pretty sure they come blank, and require service programming. When you say it goes into 4 low, does it go into low range? Trying to figure out if your issue is at the front axle or the transfer case. If it shifts into 4 low, does the driveshaft lock in and just not the front axle? There was an issue with the autotrac cases internally where the shift fork would wear out from running in auto 4x4. When it's in auto, it actually runs in 2 wheel drive, when the tccm see's a difference between the front and rear driveshaft speed, the tccm tell's the encoder motor to start applying pressure to the shift fork that engages the clutch pack in the transfer case to lock the front and rear shafts together. It's not a simple shift, it actually uses the shift motor to apply and hold pressure to engage the clutch pack via the shift fork, and overtime that fork can wear, and some have failed.