Hello,
I first, I am new to the forum and it is my first. "Ranger". In May I picked up a 2003 B4000 4.0 4x4 with 127K miles.

As we have gotten below the freezing mark, I have noticed that my 4WD does not like to engage when it is below freezing (or near to). I have read a lot of treads and watched lots of videos on the various 4x4 issues, so I have a good understanding of how the system works. I have not seen anything where cold weather affects it.

When it is warm out everything work fine.

When it is cold/freezing out:
1) The 4WD and 4WD LOW lights cycle at start up (so probably not a control module issue).
2) if I put it in neutral and switch to 4WD, I can hear the control module relays clicking (Twice I think). The 4WD light does not come on, and the 4x4 will not engage.

This tells me that the control module is not receiving the signal that the T-case motor successfully switched it to 4WD. This leads me to think that the T-case motor is semi-faulty, bad brushes? Just not sure why the cold weather would affect the motor like that.

If the 4WD light came on, and the 4x4 was not operating, I would suspect an issue with the vacuum lines to the front hubs.

It there anything else I should be looking at?