I have a 99 blazer I have owned for about 1.5 yrs and have weird issues with my 4x4..when I first got it it would just switch in to 4hi randomly when I was driving on normal road in 2wd so I would just simply hit 2wd again and it would be fine it did that about 1 or twice a week and noticed it did it more during the summer months. now yesterday I went to start it up to go plow and it would not go into 4hi or 4lo I did not hear anything below trying to engage so I disconnected the battery to see maybe it would reset and nothing! finally after disconnecting the 4x4 dash switch I played with the blue harness that connects the 4hi and it switched into 4lo and now will not go into 4hi or 2wd!! I do hear clicking in my glovebox area when I hit the buttons please help thanks

ps. I also purchased a new dash switch figuring that would help and it made no difference

 

3 button or 4 button switch on the dash?

Could be a poor connection at the TCCM. Take the connector apart at the TCCM, (Transfer Case Control Module). Carefully clean & inspect the pins & sockets making sure they are clean & tight, (they tend to corrode). Put some silicone dielectric grease on them and re connect. Post your results.

 

mine gets stuck in 4 hi sometimes and i just go and run up a curb and make it fall off real quick.

i have to jolt mine to get it out of 4-hi sometimes

now i know yours in 4-lo is entirely different as yours is in the TC and mine was in the front diff but the same principle might work.

smack it with a rubber mallet maybe as you are trying to get it to go into 2-hi

might just need a jolt and then i wouldnt mess with that 4-lo button until you figure what is causing it to stick

i realize i could be way off but its just a suggestion

 

It's a 3 button

2hi
4hi
4lo

 

If it's stuck in 4WD LO, there's a problem with the encoder motor, wiring for it, or the TCCM. Bottom line, the encoder is not shifting the transfer case. Did you try cleaning the TCCM connector?

 

If you can hear it trying to shift both at the TCCM (clicking) and at the encoder motor down on the transfer case (whirring), then you may be experiencing the condition I repaired on my Uncle's Sonoma.

 

No I have not tried anything I'm not very handy with this stuff just wanted a idea before I brought it in to the shop thanks

 

mine does the same thing, after 5 or 6 tries it comes out of it... I think the encoder is slowly going out... but I almost never use 4lo so i'm ok with it... heck don't use 4wd unless absolutely necessary...

 

is this picture what the encoder motor looks like inside? can you get the gears and things separately?