4WD high not working "check" light blinks

How cold is it currently where you live? The reason I ask is they call out in the "Retrial" portion of the attachments that it may not be possible to make the shift in cold weather. This sounds ridiculous to me but the fact that they call it out, we need to take some steps to try and avoid this.

However, the point of this is, the blinking light is telling you that the shifting is not complete. So we need to find out if the weather is very cold and if it is not then we need to follow the power through the system to find out where we don't have voltage. Clearly we have it from the switch because it is responding but we need to check at the motor. If you have it there, then it could just be the motor as the issue. However, let's start with this and go from there.

Okay. That is cold but I wouldn't think it would cause this. So we need to go to the actuator/motor and measure voltage on the motor control circuit. There are two of them so you want to check both. The way this works is the control module applies power to one circuit to apply it and then the other side to put it back in 2WD. So I am not sure which side applies 4WD and then removes it so we need to test both. If there is no voltage the the control unit is most likely the issue.