Transfer case disengaging problem, Need Help..

[scott68w]

I have a 2006 Trailblazer with the 5.3L. On ocassion when you look at the selector switch none of the lights are lit. If I move the switch to the various positions it will just keep flashing as if it was going to engage in 4WD. If I then move it back to 2WD it will stay illuminated showing what position the T-case is in. When I lock it in 4WD it works great when I put it back in 2WD though I have the following problem. Driving down the road with my foot on the gas the 2WD is working fine. If I let off the gas and coast it will make a grinding noise as if it is not completely engaged. If I stop and put the transmision in Neutral and run the 4WD selctor to 4WD then back to 2WD it will lock in and work correctly. Any ideas why it will not engage completely in 2WD? Any ideas on the selctor swich not illuminating what position the transfer case is in untill I run it through the diff options? I would appreciate any help.

[The Roadie]

The transfer case is always in the position it was left in. The control shaft can't move unless the encoder motor moves it - the gear reduction is large.

The switch may be flaky AND the transfer case or encoder motor could have internal problems that prevent commanded movements.

How many miles, and are you religious about changing the transfer case fluid every 50K? YOu also may have an issue with the front axle actuator. Are you familiar with the different noises the actuator makes versus the encoder motor? And which mode transitions trigger which noises?

[scott68w]

I have about 115000 miles, fluid is clean and I change it every year. The big issue I have is when I put it back in 2WD. It works fine until I let of the gas and coast. Then the RPMS drop to idle as if it was in Neutral and there is a loud grinding noise as if it was in between gears. The actuator noises and encoder motor all there and good. Thanks for the reply.

[The Roadie]

Assuming you don't think that's a transmission issue, noises from the transfer case are a very bad sign. If you're not in the habit of using the damage-causing A4WD mode, I'd get the truck up on a lift and have a mechanic listen closely to confirm it's a TC internal problem. If you do use A4WD mode, then you may have TC clutch fragments rattling around inside. Sorry to not give you a better prognosis, but I've been answering this sort of question for six years now.

[scott68w]

I appreciate it. Sounds like sound advice.

[dirty anton]

i had some of the same issues as you and realized after a wheeling trip i had issues with my engagement of the tc encoder motor. got a dorman for 150 and it resolved my problem. dont know if you want to jump and get that yet but i had gone through everything else at the time (electrical,tc,sw,disco)and james showed me on the os the same problem someone else was having and he remied it with the encoder motor. good luck it deff can get frustrating!

[Trail X]

Scott, does it go into 'neutral' if you're in 4WD or A4WD mode? Only 2WD mode? Do you ever notice it not driving the front wheels when in 4WD mode?

If the transfer case motor lock is faulty, like I'm guessing, then you should have trouble with it not driving 4WD with full torque.

The other possibility is a loose internal component.

If you haven't read up here on the operation of the encoder motor, do it: http://www.offroadtb.com/articles/tech- ... operation/

[MD_trailblazer]

Anyone know how to remove the transfer case as mine is making horrible clunking and rattling noise before and after I put it in a4wd but no noises when 4hi or 4lo are used I have 206000 miles and truck runs great but I'm gonna buy a used tc with 70000 miles for $250 just need to know the best possible way to get that transfer case out with out using a lift

[dirty anton]

unbolt drive shafts,wire hookups and vent hose. then unbolt from trans. i lower it down on my chest then on the ground. its pretty easy to do. when done i use gasket maker and put it on the trans side and slide the tc case back in place and bolt back up and reconnect everything.