I apologize if there is a decent post on this issue. I have searched this forum and google.

I have a 98 blazer 4.3 liter 4 door 3button on dash 4wheel drive. One day the 4WD stopped working. I push 4hi i hear a click from the TCCM in the passenger side kickpanel the 4hi light flashes several times and goes back to 2hi. I never hear the t-case engage.

So far i have replaced the Air Switch on top the transfer case, checked the accuator under the battery, replaced the TCCM and Encoder with scrap yard parts and still get the same issue. The encoders bench test find when given voltage.

I have found decent write ups on corroded wires on the TCCM, battery acid destroyed accuators and disconnected vacuum lines. I have checked all this and have yet to find an issue. The air switch on the transfer case was bad and is replaced. I can hear vacuum if i disconnect the hoses which leads me to believe there are no leaking hoses.

If anyone has had the same issue or can share trouble shooting procedure i would greatly appreciate it.

Thanks in advance,

Brodie.

 

Check out this thread:
OBD2 Non-Automatic Transfer Case Diagnostics

 

Thanks! i'll give that a go and post results Thursday.