i have a 99 chevy blazer 4x4 with the 4 button switch i have no 4x4 and a service 4x4 light on. i have cleaned the tccm connector no help light is still on
the encoder motor on the transfercase one of the mounting tabs is cracked can this cause the motor not to work? and when i push a button it just blinks

 

you have a broken hose more than likely. your front wheels are not engaging thats why the light just blinks.

to check if the encoder motor is atleast turning do this.....sit behind the wheel with the door open, put the key into Start position but dont actually fire up the engine. At that point start pressing the 4x4 buttons, hit 4HI, 2HI, 4HI, 2HI. you should hear the encoder motor turning. makesure u dont fire up the engine otherwise u wont hear anything.

if its turning then your problem is else where, which is probably a broken vacuume hose under the hood, the one that goes to the air baloon under the battery. should be an easy and cheap fix.

 

mine just started to do this same thing but. when i tested it like you said it made a small bang sound??? under the truck.. i have checked the vacuum lines and every thing in between too.. still no four wheel drive..

 

Check out my build thread I had the same issues mine was a bad vacuum but I eliminated it and now it works prefect every time. It may or may not be an option for you but I figure I would throw it out there.

 

thanks im going to pull in the shop and look at it more in a min..