For months I have been the designated forum reader and decided time to ask for help. My son has a 2000 blazer LT and the 4wd is out, won't shift into 5th so it sits in my garage and my son has my car! My hubby stays in the cold garage all hours of the night and we have bought every part known to the auto store for this thing. We replaced the tccm, the actuators, the computer, the solenoid. Still not working. My husband says the tccm doesn't turn but its brand new, he is trying to figure out how to test it? They swear it has no holes in the vacumn. They are tired of me yelling out "have you tried...cause the forum says?" Any help is greatly appreciated as I would love to have my family back as well as my car! Family on a budget so can't really run to the dealer....thanks in advance

 

You didn't mention the mode selector switch. Have they changed that? This is what was wrong with my 2000LT and is a frequent culprit.

http://www.autozone.com/autozone/par...421244_0_10878_

 

^^ fixed my 2000LT as well

 

check the wiring harness that goes to the tccm. i had a similar issue, and after a long time finally figured out that the harness was split from the heat of the motor burning through it where i couldnt see it.

 

hey thanks for the replies..they did replace that switch, twice I think and checked the harness. Last night they found that there is something pushing 1.5 volts through a ground wire that is shutting down the system? any clues where to go from here? just saw our weather and looks like snow..but its Indiana so that could change...thanks everyone!

 

How many buttons are on the switch in the dash? Does the switch look like the picture posted above?

 

Another thing is when was the last time the truck was put into 4x4? There is a sleeve gear in the front differential that will get stuck in the open position if the truck hasn't been put into 4x4 very often. Also check to see if the transfer case is actually going into 4x4. If the front diff doesn't lock in but thet transfer case engages you won't have 4x4 but the front drivesahft will turn.

 

This is the husband, thanks for helping the wife..Thought I would give her hand explaining what we have done... so far the system has a 4 button auto 2hi 4hi and 4low. Going in to the winter we replaced the front vacuum actuator when manually squeezing the vaccum actuator a couple of times it started working, well for a day and it quit working again so I took the cable actually off that goes to the front axel and checked it out to make sure the cable wasn't siezed up. I lubed up the cable and jacked up the front end and manually pulled cable to make sure the front hog head would engage and it does but the transfer case motor started buzzing when you pushed the button. So i purchased a new one. then the computer located in passenger sided started clicking and we read this is common. I also found that the 2 connectors that connect to the computer have tons of corrosion and 1 of the wires was broke so got a new clip from junk yard but unfortunately after I cut all 26 wires I realized that several were the same color (oops) so i got the original wiring schematics, purchased the new computer and wired it up, now the motor doesn't respond and the lights on the controler won't light up either. We have also tested the front and rear speed prop sensors and replaced the front axel solenoid. What we have figured out so far at this poinnt is one of the ground wires black w/white stripe the wire in the clip is #E16 circut number 451 is ground but it actually giving us feed back meaning if we check the that wire to another grounding source we get a feedback of 1.4 volt which shouldn't be happening (I am assuming ) So my next step is going to be to check all of the wires not connected to the computer and make sure none of the wires are shorting out or are touching some where else do to corrosion some where along the line. Any other help out there?

 

Double check the wire splices to be sure the colors didn't get mis-matched. The schematics you have or these should provide the pin numbers to trace the harness- it sounds like the black w/stripe was spliced wrong and the one you should have providing the LED illumination is not getting powered either.

https://blazerforum.com/forum/tech-articles-diy-29/nv236-wiring-diagnostic-information-41198/

 

ok the black with white stripe wire (E16) as i said befor was giving me feed back so what i tried to do was this i took the wire off of the clip to the computer and spliced it and ran an isolated ground to it the i took the same wire that was connected to the motor and ran an isolated ground to that as well that worked, but i'm not sure if i should just wire it up that way or if i should try and locate where that ground wire is bad and fix it, which would be a big job. the only thing the schematics say as to where it would be located is body relay block but i'm not sure where that would be. any ideas or does that also mean that the body relay block is possibly bad?