The wiring for the transfer case speed sensor can fail causing sporadic operation of the AWD (All Wheel Drive) system.Google+
Car Problem Reports
Saab 9-7x Sporadic Operation of All Wheel Drive System
Saab 9-7x Problem
Average Mileage: 90,823 mi (74,000 mi - 110,000 mi)
Visitor, 2007 Saab 9-7x, 110,000 mi
Only rear wheels provide traction in snow- 4WD does not automatically engage as it should
Visitor, 2008 Saab 9-7x, 74,000 mi
Had to replace front differential. The transfer case encoder seemed to be the issue after all said and done. Wheels would lock or shutter when turning into a parking space. It felt like a 4wd truck engaged and then suddenly driving on clear asphalt.
Visitor, 2006 Saab 9-7x, 90,000 mi
The all Wheel Drive seems to be trying to engage when I stop at a Traffic Light that is on a slightly downward slope. I feel a slight nudge click several times. I this the speed sensor, transfer case, transmission. I am ready to do a Transmission Fluid / Filter change and though maybe it is a Hydraulic thing. The vehicle runs great other than that. My tires all match and shift great moving.
Visitor, 2008 Saab 9-7x, 103,267 mi
When I'm driving And i turn left or right. The car stops or staggers, or locks up. I can't pinpoint if its all wheel drive problem. I've taken it to shops, yes I've taken to a couple different shops and they think rear differential needs replaced(oil) or transmission. I think its what the problem says up top!!
Visitor, 2005 Saab 9-7x, 84,000 mi
NO traction at all in the snow/ice. It is supposed to engage when the back tires slip...only one of my tires is spinning.