Hello!

I'm havin a pain in the a** at this moment. My dad's 99 blazer is stuck in 4 low and i cant seem to do anything about it. Here's what happened, to make a short story. I replaced the rear output shaft seal because it was leaking for a while. Sadly i realised transfer case was empty after all this time. (truck was barely used, and drove in 2wd 99% of the time.
Did the job, refilled the t-case with Redline MTL. Drove alright except for what seems to be full diff lock front and/or rear in 4 hi/ 4low while turning (driving straight is alright, turning seems like something is binding). Anyways, it's a detail at this point!

I went for a quick test-drive with the above mentionned conditions, and could switch without problem from 2-4hi-2low. I shut down the truck and disconnected the battery to check the vacuum actuator under the battery, and when i started it back up, it would not bulge from 4 low, where it was when i shut it down.

When i try to make it switch, i hear the 4wd computer clicking, then i hear the transfer case motor buzzing about 2-3 times, selector switch light flash and i'm still on 4 low..

anyone got a clue WTF is going on!?

 

btw i removed the t-case motor, there was mad buildup of calcium between the motor and gasket. I could not seem to move the transfer case shaft with channel-lock plyers (maybe will have to move the truck to give a chance). t-case motor will not move by hand either. When i tried re-installing it, it seemed it was badly aligned and i cannot put back the motor back on.

 

there is a diagnose section for the 4x4 system in the tech area.
is the vac actuator ok? maybe it was shifted or the vac line is loose. can you move the cable by hand going from the actuator to the front diff?

the noise you hear while turning in 4hi or low is normal for the most part...if you have traction, like dry pavement your going to hear it binding up...really only for low traction use.

 

I checked the vacuum actuator (under the battery?), when i start up the vehicule, it pulls the cable automatically (stuck in 4x4..)

i'll check the section you speak about

thanks!

 

Currently experiencing the same issue, started this morning and found my 2000 nv236 4 botton TC was stuck in 4 low. It'll switch out of 4low into 4hi or auto, but goes right back to 4 low. No idea where to start looking for trouble. (Currently searching stickys) Please post a fix if you find one.

 

Please post a follow up on this topic if you found the problem...

 

sorry no update yet, i can only work on weekends and weather wasnt on my side... I tried pullling the encoder motor apart (casing was warped due to salt deposits..) cleaned everything, seemed fine. I made a hole in the electronic sensor on the motor and shot electrical contact cleaner.. Went to try it out, battery dead. While i was charging the battery i tought i'd clean the starter contacts, broke the main 12v pole of the starter solenoid.. So no, no results yet.

Sorry guys but i hate this P.O.S truck!

 

Been ******* some issues like this myself. Try replacing the selector switch on the dash, when mine was messed up the lights went out. Also there is a vacuum switch (on my 03 with auto 4wd, not on my 99 with 3 button switch) on the firewall that I unplugged and plugged back in. Also check fuses, in the fuse panel under the hood it is marked ATC.

Hope this may help

 

For those that are stuck in 4lo, here's a trick i found earlier today.

This is directly from my 2004 owners manual:
SHIFTING FROM 4LO TO 4HI OR 2HI - "On automatic transmission equipped vehicles, if your transfer case does not shift into 4HI, your transmission indicator switch may require adjustment. With your transmission in NEUTRAL (N), press and release the 4HI button. While the 4HI indicator light is flashing, shift your transmission into PARK (P). Wait until the 4HI indicator light remains illuminated before shifting your transmission into gear. This will get you into 4HI, but you should take your vehicle in for service to restore normal operation"

I guess it's some type of TCCM over-ride command, limp home type of thing.

I don't know if it works for all years, but I hope it's helpful to someone.

 

i dont know if i really did fix it, but when i re-installed everythin it worked. Case solved i guess, i just wont turn off the truck while still in 4x4 mode (high or low, just in case!)