I have read a lot on this, but still have trouble. After a couple of times going in and out of 4HI, and 4LO on my 2004 Blazer with the 3 button 4 wheel drive, I then cannot get it out.
It's either stuck in 4HI, 4LO, or 2HI. If I disconnect the battery, then reconnect it, the 4 wheel drive system works fine again for a few times, then gets stuck again.

I replaced the TCCM and it still does it, only it seems with the new TCCM it goes in and out of the 4 wheel drive more times before it gets stuck as opposed to the old TCCM.
Also, it seems to go in and out of 4 wheel drive smoother and on the first try with the new TCCM, as opposed to the old TCCM. With the old one, I would usually have to press the button at least twice to get it to go into gear.

 

did you clean all the terminals yet on the tccm harness and encoder motor harness?

what does it do when it stops working?

does it just click, do lights flash or nothing at all?

 

actually no i didn't clean the terminals on the harnesses. They did look clean though.
when it stops working, it will be stuck in either 2HI, or 4HI, and when it is stuck either the light on the dashboard switch is illuminated of the gear it is stuck in, or all of the 4X4 lights turn off and stay off. when i press the buttons to try to switch gears nothing happens, no clicking, and the light for the gear button i am pressing does not light. its like its frozen in the gear its stuck in.
the only way i can get it to work again is when i disconnect and re-connect the battery.

 

Although I have not read about this happening, it sounds like the encoder motor is failing once it gets hot. It may just be a design feature of the encoder motor that it shuts down if it gets hot as normally there is quite a bit of time between changing of mode (4HI to 4LO or 2HI).

Do the lights in the 4x4 selection buttons stay lite when 2HI is selected and then 4HI allowing for several minutes inbetween mode changes?

I know that I had to resolder all the connections on the 4x4 buttons in my '02 in order to get the lites to stay on and the buttons to work.

Also odd that your '04 has the three button as I thought this was the older version. Makes me wonder if someone put the wrong buttons in at sometime??

 

I had to do the same in my 99, I think this would be a good place to start

 

No, the lights go off properly as they should when selecting 2HI and 4HI.
There was an option for 3 buttons and 4 buttons (with auto select). Mine has always been the 3 button. I know this because my father was the original owner of it, and it hasn't been changed.

 

Start with checking/cleaning the connector terminals at the TCCM. Next I would resolder all the joints on the 4x4 selection switch. Easy to do, just be careful taking the two halves apart...plastic clips are easy to break.

If after this, then likely time to replace the encoder motor.

Let us know what you find out.

 

Ok, I will resolder the joints on the selector switch.
If this is in fact the encoder motor, will it eventually fail altogether after a while?

 

How quickly are you switching between modes? If say 4HI is selected, then 5 min later 4LO, then 5 min later 4HI....then 10 min later 2HI....does it work or does it get stuck?
If you are switching modes five, six or more times within 10 minutes, then the motor is likely overheating and shuts down.

If it is the encoder motor failing it will eventually just completely stop working at some point. But if above does work, then it may last a long time as long as mode switching is not too quickly.