Hello All, I am a new poster here and hope someone can assist with this diagnosis.

I have a 2 door 1999 Tahoe z71 sport 4x4 that is stuck in 4wd. I had replaced the actuator at the differential a few years back so I wanted to know how to diagnose if it is that again or the TCCM..

Here is what its doing. It is in 4LO, and when I put it in neutral and try to switch to 4HI, 2HI or Auto the light blinks, but the light for 4LO stays lit up. There is a clicking under the dash when I try push buttons to shift.

I have unhooked battery for 30 minutes, removed the ecm1 fuse for 40 seconds, cycled ignition switch 5 times to clear..... but it still does the same thing...it is stuck in 4LO. I removed the Actuator and its piston can be pressed in and pops back out. Before I spend the money on a new TCCM or another Actuator, I thought I better see if anyone knows how I can diagnose this.

Also, is there a manual way to push in the differential plunger (where the actuator sits) to MANUALLY put this in 2 wheel drive?

Any help will be appreciated.

 

Can you just shift the transfer case with actuator removed. If the actuator is mechanically rolling the transfer case back, leave it out till you can get a new actuator.

 

That is what I am wondering. How far or how many times do I press it in to make it go into 2wd?

 

Since it doesnt seem that this forum is active or has info, does anyone know another forum that may have the info I need?

 

I might be wrong, but isn't the shifter on the transfer case where you could just use a wrench to move it between modes?

 

It is a plunger type apparatus. And I am hoping that the thing can be pushed in manually but dont have a helper right now so was hoping someone here knew the procedure. I am getting the impression this isnt a high traffic forum.

 

Have you tried youtube? I am not familiar with your transfer case. I had a 2000, this was an actuator that attached to the shifter shaft external to the transfer case, use a crescent wrench to shift it manually without the actuator.