i have 2004 Chevrolet Silverado 4x4 z71 extended cab and the service 4wd indicator is on.
when i start my truck the lights on the 4wd switch comes on and then goes right back off. so i changed the switch and that didn't fix the problem so i changed the transfer case module and still doing the same thing. any ideas?

 

post the codes set in the transfer case control module.

 

what codes

 

if you have a fault in the 4wd system; the module that controls it may detect a fault. checking for codes is the starting point

 

i hooked it up to my obd2 and no codes

 

I'm having the same problem, 2004 crew cab 4X4. I only have 70,000 miles. I ready replace the button switch know I don't know what to do or just take it into the dealer?

 

I had the same problem with my 2005 Z71 off & on for the past 3 years. This past December I finally had to deal with it. Luckily it hung up in 2WD & not 4LO. I had come across a youtube video showing how to check the dash switch. I went through that process & all ohm readings were perfect. I had a shop pull the codes because the std code readers can't read the 4WD codes. I can't remember the code but it pointed to the inducer motor. They wanted $650. I have read of guys paying more. I had also read a post that I will try to quote. "If your 4x4 works fine most of the time, it isn't a mechanical problem. It's an electrical problem." There is a sensor inside the inducer motor that costs about $50. I pulled the inducer motor & put in a new sensor. It has run fine for 3+ months.

 

...encoder motor
do you have a pic or part number of the part you installed

 

Here is a pic of the sensor & the inducer motor gasket as well as the motor that it fits in.

 

On my 2004 crewcab that I just bought two days ago the service 4wd in the message area comes on and off but the 4wd works perfect. Should I replace this sensor?