After many years of cycling the 4WD selector switch it got to the point of not resolving itself. After observing the voltages (fluctuating) with the Tech 2 I ordered a replacement switch but in the meantime I disassembled the original switch, cleaned the contact surfaces and it then worked fine. I found it fairly easy to do. I haven't used the vehicle a lot since so right now cannot confirm how permanent a solution this might be but it doesn't cost anything but a little labor time.