4 wheel drive issue

[tricia52369]

I have a 99. Last winter I discovered that the transmission doesn't shift when the 4 wheel drive is engaged. Sometimes when the transmission heats up it slips in 2nd and 3rd gear. I just replaced the transfer case speed sensor and put in fresh fluid. Now the 4 wheel drive won't even try to engage. Any ideas?
Your help is appreciated. I thought the two problems might be related.

 

[lesterl]

Manual or Electronic transfer case?

 

[tricia52369]

Manual or Electronic transfer case?

Electronic

 

[lesterl]

recheck your speed sensor, connections, and the tcase module under the dash....