I had seen a few posts that people were having problems with the 4WD on their 94 Blazers not engaging. If you put it in neutral and push the 4WD button and it flashes 5 times and/or it sounds like it engages when you are in neutral then this is probably what it is, if it is not the switch or TCCM. Hope this helps you out.

I took my 1994 Chevrolet S10 Blazer Tahoe LT to the Local Chevy Service Department. It was the Transmission Case Encoder Motor.

$142.99 at Advance with a $20 core charge. GM has the part but it is $500 and will take a few days to get there. It cost total to track down the problem and put the new motor on $258.00 Total bill for part and labor = $388 at the Chevy Service Center.

So if you are having this problem and it is not your switch, vacuum lines or TCCM then it is the Transfer Case Encoder Motor. Hope this helps someone else that has this problem