i have a 1999 tahoe. no 4 wheel drive.when i push the 4hi button it will blink a couple of times then remain steady but no 4x4. when in 2hi the front drive shaft will turn free when i hit the 4hi button it will not turn seems to be engaged but no 4x4 just rear wheel drive. what do you think encoder motor problem?

 

could be encoder, could be actuator at front diff. however, if the driveline locks in, then i would rule out the encoder. for the most part anyway. gm's are notorious for having the actuator on the front axle go bad. most parts stores carry, about $75-$100. really easy to change.

 

front actuator works,replaced the transfer case motor all fuses good still no 4x4 any ideas?