Hey guys. New to blazerforum and this is my first thread. I have a 1999 Blazer with the 3 button electric shift 4x4 and he past few days it has been givin me problems and will not engage. when you push the 4HI or the 4LO buttons it just flashes and will not engage. I can hear the TCCM clicking but nothing...I have already changed the vacuum line from actuator to T-case and the actuator itself. I plan on draining the transfercase fluid when i get a chance but what else could possibly be going wrong that I could check out before taking it to a shop?

 

A couple of things come to mind from experience...

It could be the switch on the dash is acting up. I have a 99 that did this and found out it was throwing a code when I jiggled it while pushing 4 hi, so I replaced the switch but still had problems.

Found out it was the encoder motor. After replacing both the switch and motor the 4x4 worked fine. These encoder motors are junk on these vehicles. I've had 2 blazers a year a part and both went bad. Two friends with similar years had same problems. Ridiculous price for OEM replacement too. Don't do that, the aftermarket is producing them now and much cheaper.

 

I replaced the switch in the dash today but still gettin a code for a small evap leak. Could this be causing the problem? And does the encoder motor control the vacuum?