4x4 does not work

i have a 2000 blazer and the service 4wd light comes on and stay on and 4x4 will not work check fuses and all are good dealer said something about the sensor but dont know what and where the sensor is that runs the 4x4 could someone help me out. and how hard of a job is it to change the sensor


thank you

It's either your a sensor on top of your transfer case or your vacuum actuator (under the battery tray).

The sensor on your transfer case is a five minute job. Go to NAPA to get the switch, as it's half the price there.

When you replace the switch, you need to make sure the vacuum lines going into the new switch match up. There should be a slot in the plastic harness that plugs into the switch.

Check the encoder motor also, located underside.