The wife's 97 didn't want to shift into hi or low range this morning. Np233 three button tc. It was -2 degrees this morning so that may have been part of the problem lol. After messing with it for about 5 minutes it finally went into 4x4. Any ideas what to check?

 

I would start by taking the battery out, removing the battery tray, using jumper cables to connect the battery (which is now outside the truck) to the battery cable terminals, start the truck and have someone switch between 2WD and 4WD while you watch the vacuum diaphragm (looks kind of like a flying saucer with a cable sticking out of it). Should suck in smoothly and not sluggishly.

EDIT: Insure you are careful that the jumper cables and battery cable terminals do not touch together and start throwing sparks.

 

Thanks for the response. I should be more clear on the description of the problem. I know its not the actuator. That is working as it should. The tccm is clicking and the dash lights are flashing. I can hear the encoder motor trying to move to shift the case. I was just really wondering if the cold would be affecting anything? It shifted fine after a few minutes of messing with it and has worked fine the rest of the day.

 

This is just my opinion but I am inclined to think the problem is the 4x4 mechanism and not the cold. Where I am it is about -28 Celcius (-18 Fahrenheit) and my 4x4 works fine.

However, my 4x4 did not work fine in the fall so I looked over the whole system. To directly respond to your question, here are some ideas to check. Vacuum lines, actuator, dash switch, transfer case control module and encoder motor. Check the "sticky" in the DIY tech section, it gives a few other ideas like wiring or the transfer case or front differential itself.

In my case, I thought the dash switch was working because lights were flashing, but in fact the switch was failing. I removed the switch and re-soldered each one of the joints. Now the lights are bright and the switch works great.

I also though that encoder motor was working, but in fact it was probably not. I removed the encoder motor and cleaned and lubricated it. This involved drilling holes into the case and spraying in contact cleaner and working the motor back and forth with test leads connected to the battery. I did not think this up on my own, I found instructions on the S-10 forum. As it turns out, the motor was squeaky and sluggish. But after cleaning and lubrication it zipped back and forth very easily.

So to me, the switch and the motor are easily repairable and are worthwhile checking after confirming the actuator works.

Also, I had a broken door jamb switch. In other words, the system thought that my door was always open! I suspect this may also have been interfering with the 4x4 since it's on the same circuit. So you might want to check your door jamb switches.