I am currently having a problem with my 04 Z71 1500 Crew Cab.. while driving today,a Service 4wd flashed across the odometer screen then, the auto 4wd light began to flash repeatedly... this was when I was travelling at around 45 mph... I then pushed the 2 wd button, it flashed about 10 seconds or so.... then the truck went into Auto 4WD...however, the truck is in fact in the 4 wd mode. Upon turning a corner the front differential is "grabbing" just as if it was in 4wd. I have read a few threads on here with people discussing similiar problems and solutions. Everywhere from the switch on the dashboard to an encoder motor.....Please help, need to get this resolved ASAP..only vehicle that I own for transportation.

 

I've been living with this same issue with my 2007 Silverado 2500 for about a year now.

I just recently NEEDED my 4wd but couldn't get 4x4 cause I was getting the DIC (driver information Centre) message on my dash "SERVICE 4WD" I crawled under the truck and tapped on the actuator on the transfer case until it engaged. I'm pretty confident my issue is my T case actuator needs to be replaced

 

I also have heard that it may also be a switch problem, or a grounding problem.

 

When I consulted my dealership, they said it was my switch too.
But I find it unusual that it will eventually shift if I tap on the actuator

 

in2trux...have to agree with you...I have seen a lot of weak encoder motors.


to the op...try jiggling the buttons on the 4wd switch....if they start to work right... the switch is bad. if you have access to a full function scan tool, retrieve the dtc in the transfer case control module.

 

Problem solved!!!! Bare wire was hitting on the frame. Re-soldered,shrink tubed everything is working great.

 

Lucky !!!!! Cheap and easy fix $$$$
Glad to hear you were able to save your self an expensive repair

 

Me too...Christmas is coming up.

 

What wire? As my 4x4 don't work either.