AWD light stays on, after $2000 work. In 4wd when it wants to be. Brake&ABS on.

What is your question?

So called "ScartTrac". Supposed to use wheel-speed sensors, a drive speed sensor, and a computer to decide if wheels are slipping, and the vehicle needs 4WD. I've had encoder motor changed, new 4 tires, oil in encoder motor changed...no scanner (repair shops) shows a cause. Can I just turn the encoder and have a 2WD truck? Can I put a simple "2WD-$WD" switch on the dash to energize the encoder moter to shift to 4WD when I want to?