To those who said replacing wheel speed sensors won't fix the problem I will say that you were right. The only ABS code that comes up is C0455, and that's for the steering wheel position sensor which interacts with the ABS as part of the StabilTrak system.

We went for a test drive with the scan tool hooked up and it showed the wheel speed sensors all reporting the same speeds, so it would seem they are not faulty. I found it interesting that the ABS system uses both front sensors but only one rear while the StabilTrak system uses all four. I only know this because the scanner shows different screens for those two systems.

During our test drive the steering position sensor seemed to be working as well as it recorded 0 driving straight and either positive or negative values depending on whether turning right or left with those values changing with the degree the steering wheel was turned.

Also the scanner showed the vehicle as being in AWD mode during the test drive. There isn't any ice around anymore for me to test whether the vehicle performs properly in low traction conditions, so I don't know why it wasn't working properly the other day.

My son cleared the C0455 code so I'll wait and see if any other odd behavior shows up.

The scan tool he had was really nice. I thought those things were vehicle specific but it's not. When he plugged it in it found my VIN and loaded up the appropriate screens. But it's also a $500+ tool that would be hard to justify the expense for the few times I'd need it working on my own vehicles. I was surprised to see how many sensors of various kinds there are in my 18 year old vehicle. I'm sure a newer vehicle has a lot more. Nice when they work, but additional failure points when they don't.

 

and then you change another part, and another part, and another part ... Now your wallet is empty and you still don't know what the problem

 

AWD is a full time system (just like you showed in your picture). That means it's always on.

 

Cost of a quality upgradable scan tool will be gotten back after one trip to the dealer and upgradable means it's a long term tool investment going forward if you are going to repair your own vehicles.
Anything other than routine maint. requires a scan tool today. Wait until you need a scan tool to reset electronic parking brakes of current vehicles after a rear brake job.