Wide Open

I am looking for some electrical assistance with the operation of a 00 Autotrac transfer case from any and all electrical geniuses.
First a little background - Currently I am using a 07 AWD transfer case from a Denali/Escalade behind a 6.2/6L80E combination.
On pavement (wet or dry) I have traction at all four tires. I can spin all four tires so I know it works at least in those conditions. The problem arises when I get into slippery conditions. In the snow the rear tires spin excessively before power is routed to the front wheels. In mud no power is applied to the front wheels unless I use the parking brake to load the rear axle, then power will route to the front. The 07 transfer case appears to be heavily dependent on Traction Control to route power to the front driveshaft in slippery conditions and this doesn’t work for my needs.
I want to switch back to my Autotrac transfer case so I can select 4WD when needed. I know I have to swap the input gear for the 80 series but before I go to that expense and hassle I need to get the transfer case shifting. The wiring harnesses for the engine and transmission is separate from the wiring harness for the Autotrac case (the AWD unit has no electrical connections).
Problem statement: I connected all the original wiring to my Autotrac transfer case and the dash switch lights up when the key is turned to the “run” position but the transfer case will not shift. When I pulled it out of the truck I set it to Neutral and it will not shift to 2WD, 4WD Hi, 4WD Lo, or Auto. Does anyone have any idea how to get the case to shift? Is it somehow dependent on the Park/Neutral safety switch? Any help would be appreciated.

Bish

I believe the 07/08 transfer case is ENTIRELY reliant on stabilitrac to engage the front. The Borg Warner AWD t-case on the GMT900's is an open differential type. Once a tire is spinning, the stabilitrac applies the brake to the spinning wheel and that then applies power to the fronts. I can feel this in bad traction situations like snow or mud. Even if I disable traction control AND stabilitrac, it still brakes the spinning wheel to apply power to fronts. Poor choice of designs especially compared to the NVG t-case they used to use in the AWD models.

Now onto your shifting question. The only thing I can think of is the TCM. Since the TCM is inside the 6l80E, your main computer may be confused. On your 4L60E, the transmission controller is external and as such may have something to do with why it won't shift. Just guessing here but that's what I could come up with. Custom programming may be one way to resolve it.

Wide Open

OK, I understand what you are saying about the Traction Control/Stabilitrac but what has me so confused is that on pavement, wet or dry, I have power to all four wheels. On dry pavement if I stab the throttle I can feel the front tires spin just a bit in first and second. On wet pavement all four tires will spin uncontrollably from a stop. BUT, unfortunately there is always a but, when I am in slipperier conditions it seems to lose its will to power the front tires. That is when I have to apply the parking like which would be like the Traction Control/Stabilitrac like you mention.

Now, are you saying that if I find a AWD transfer case from an earlier vehicle my problems will be solved? If so, what type of vehicle? GMT800 Silverado SS, Denali, Escalade? This is so frustrating because my 97 Bravada AWD works much better than what I have in my truck.

So you have me thinking about the TCM deal. Since my 00 has a PCM instead of an ECM and TCM I might be in luck for the Autotrac. I use the E38 ECM to run the engine and interface with the 6L80E’s TCM. I use the original 00 PCM to power my fuel gauge and water temp gauge so it may be as simple as tapping into the PCM pins to control the T-case. Now if only doing it was as easy as typing it I would be in great shape.

Bish

Mine is fantastic on dry pavement and all 4 tires hook up great. I get minor slippage on wet conditions if I hammer it but then it starts modulating the brake all by itself to get better traction. In snow it feel lazy and not smooth. I don't think you have the traction control/stabilitrac working properly for that setup. I know the prior year NVG149 transfer cases worked significantly better at least from my experience. I don't have any idea if it would match up but I know of at least one other that is waiting for a guinea pig to try. I will say that I am very disappointed in the change to borg warner for the gmt900's I am not impressed with how it PREVENTS me from driving in certain situations. Sometimes its ok to spin the tires you know!!!!!!

Chevy Cowboy

iTrader: (5)

manual shift case ftw!

Wide Open

What does ftw mean?

Wide Open

Does anyone have any other suggestions? I don't want to go to the manual case.