Not Another Bad 4wd Actuator Thread. Trust Me!

[Sambo_Eddo]

I am hoping that someone here will have the answer for me on this because I have searched all over and can't seem to find anyone who has my same problem. I'll try to keep this as concise as possible while still providing as much info as I can. For starters, it's a 2002 Tahoe LT. I noticed since winter hit that my fwd does not work. I can push the "auto 4wd" button or the "4wd hi" and "4wd lo" buttons and you can feel the transfer case engage. The lights on the switches do no flash at all once the transfer case is engaged. The light stays lit on whatever option I have pushed. I have the understanding that this is how everything is supposed to act and look. I throw the truck on the list and raise it up expecting to find the notorious "bad electronic solenoid". I unthread it from the differential, plug it in into the harness and push the switch on the dash and the solenoid does push out. This tells me the solenoid is good. Next I try to manually push the front differential engaged by pushing on the metal shaft inside the hole that the solenoid threads into. The shaft is solid and will not move. Next I remove the differential housing that encases the 4wd shifting mechanism. Once apart I can see that the shift fork is stuck solid on the metal shaft that it rides on. I have to actually knock the fork off of the shaft using a hammer. Once off the shaft there appears to be a slight shoulder on the shaft that the fork had slid onto and obviously no longer slid freely. I spoke with the local parts department at our Chevrolet dealership and they seemed to have an attitude as if this was a common problem. We took a look at the diagram for my truck which I will try to picture below. According to that diagram I was missing one of the springs that sits on the metal shaft. I will circle the springthat was missing in the picture below. I ordered this spring and received it a few days later. Now comes the tricky part. I install the spring as pictured in the diagram reassembly everything exactly as it was removed (matching the diagram as well). Once back together I try 4wd and am now stuck in 4wd all the time regardless of what the lights/switches show. I lift her back up, tear her apart and find that with this new spring installed simply threading the electronic solenoid into the transfer case already pushes the metal rod, and in turn the shift fork into "4wd engaged" mode. This is where I was baffled and could not figure out how installing everything exactly how the diagram showed would cause such an obvious "misfitment" of parts. My only theory is that there may be different models of the electronis solenoid that are not all the same lengths and that someone along the line has installed one that is incorrect for my year or model. I don't know if all of this sounds like gibberish or if your familiar with these front differential 4wd mechanisms enought to picture what's happening here. I can take pictures of anything if my explanation makes no sense.

 

footnotes:

4wd switches work

transfer case works

electronic solenoid works

assembling the front diff 4wd mechanism causes the gears to be fully engaged at all times.

[gmtech4]

something was put in backwards i think,shift collar or fork,

 

terrible pic lol

[Sambo_Eddo]

The fork looks pretty much straight..as in you could flip it either way and it would make no difference in where it places the shift collar. It's basically as if the new spring installed is too long. It doesn't allow the fork to sit low enough on the rod. So when you thread in the electronic solenoid it's already pushing the fork into 4wd position.