4 Wheel Drive Engaging Problems

[fossel]

2004 Silverado 2500HD 4X4 6.0 litre. when engaging 4hi on the fly the gears don't syncronize they grind. The 4 wheel drive works fine 4Hi and 4Lo. This is NOT an auto 4 wheel drive, just 2Hi,4Hi and 4Lo Front diff. actuator works, encoder is working. Drained T-case, no fragments. I have replaced the dash switches and the encoder sensor. Haven't gone to get codes read. Do the front wheel ABS wheel sensors have anything to do with the sycronizing??

[jro909]

its because the teeth aren't lined up, try lurching forward and engaging 4x4...