Pictographical Referencing Systems...
 

i'm on it. ill trace mine out for you real quick. give me 5 minutes or so.

the vac res ball looking thing is on the older blazers. yours is a 99. mine is a 2000 so it should be a similar set up. (i have the 4 button though...)

anyway hang tight. BRB


**EDIT**
:icon_nic:

pics below with explainations in their titles FTW!

banging head against the wall
 

thanks for those great pictures! I found out that the little black panel on the fender actually has a fitting on it, with the canister on the back side (literrally inside the fender). I hooked it up...... Still wont go into 4x4. I bought a chilton guide hoping for a vac diagram, no such luck. Im going to replace the switch on the front rear end on the right side where the axel shaft is. Im so aggrevated, I was going to sell it today! Everything is in perfect shape except for that. Any other suggestions?

Combs, I'm right there with you...


Found that fitting, hooked the tubing up. Still got nothing.

Right now I have everything hooked up ( to my knowledge) and have the battery unhooked.

Gonna read some more and let the battery sit for a little while, maybe we can figure this out?!

screw it. Going to junk yard to get tccm. Be back with update later.


-hp

on the drivers side top of your transfer case you should have a fitting with three hoses running to it. one hose connects to the tee by the brake master cylinder,off the tee one goes to the vacuum res. the other should go to a fitting on the intake. other small line coming from transfer case goes to the front axle engage solenoid under the battery tray.the third slightly larger line i havent figured out yet (i lose it as it goes into the engine bay ).
any kind of vacuum leak will make the 4wd and heater controls do strange things .

i'm working on the same kind of problem with my 96. i hope this helps and maybe we can all figure out our problems .

on the transfer case is a vacuum switch. if its stuck or bad things wont work.

2000 blazer stuck in 4 wd low as well
 

Sorry to beat a dead horse.. I read the the blogs this morning. Basically my wife tried 4 wd low to get up the driveway... light just flashed and then all the 4 wd lights went off and the check 4wd light came on. I went down the driveway and started the truck up.. Noticed it was in 4wd low. I have pulled the ATC fuse, reset the computer checked the pins on the module in the kick panel... no luck. I can hear the module clicking and signaling the long black "motor" on the transfercase... the "motor" just whines and gurgatates... Im assuming I have a bad "motor"... Any help would be greatly appreciated?

Latest update
 

Aight guys, here's what I got.

You called my bluff, didn't go get a new TCCM. Decided to play around a little longer, to see if I could find anything one last time it,

I checked the valve underneath the battery tray, unhooked it..Checked the hose connected to. The hose is sucking air and that valve beneath the battery tray seems to be working..

Now my next assumption that it be the encoding motor??

Took the plate covering the encoding motor ( on the transfer case) but never did take the motor off. Decided to check with you guys first.

I mean, when I crank the engine, heres what I have observed:

1) TCCM clicks twice
2) Buttons stays lit continuously in 4lo
3) Encoding motor grinds for a quick second
4) No air coming out of any hoses.

I've amatuerly narrowed it down to one or the other: Encoding motor or TCCM.

Any pointers on how to determine between the two which one needs replacing would be great.

Or if I'm completely in the wrong direction, that would help too.

Waiting on you guys until I make a move.

Thanks alot,

-HP

blazer 4x4 service light stays on.
 

hi there.i have changed the encoder motor and the tccm,and still no 4 wheel drive.getting a code 308 a/b circuit low.anyone with an idea what that means.

thread :icon_pirate:'s every where...

To give you a simple answer would be extremely hard without looking at the truck. This problem is usually a transfer case problem, and could be as simple as a linkage problem. Some of vehicles use a vacuum, or electrical switch/solenoid on the transfer case, which has vacuum, or electrical lines running to the front differential that can be pulled loose, or the switch itself can be faulty. If your transfer case is shifted electrically, then it may be just a bad ground to the transfer case. These problems can be traced out fairly easily.

I would suggest that you purchase a repair manual, and try to trace out the front wheel drive section, starting with the front hubs. A Chilton's or a Hayne's manual can be purchased at most auto parts stores for $20, and they have a lot of information on basic trouble shooting, and repairs. These manuals are designed for a year or range of years for specific vehicles, and are invaluable if you are planning on doing any repairs yourself.

Another thing to try, would be to have the transmission, transfer case, and differentials serviced. This is simply changing out all of the fluids.
There is a slight chance that there are some dry components that are causing some drag on the shifting mechanism.

I have a 2001 blazer. I went to use the 4FWD and the lights would blink on the switch. Reading from several responses on websites, I found that it was a broken vacuum line at the switch centered on the firewall that goes to the actuator that engages the front axles. The actuator is under the battery support plate. The way the vacuum line was run made for a very tight bend at the switch on the firewall and that is where it cracked, I moved it to eliminate the bend.

had that same issue with 01 just by happen stance earlier this morning while checking fluids i noticed a vacume line disconnected up near the firewall reconectted it and i'm back in business. the line is back of engine compartment close to the firewall about center. there are two lines plugged into a plastic houseing with two hose nipples and two electical plugs the bottom hose nipple was my problem.good luck hope this helps

my 2002 blazer is stuck on 4 wheel low, yesterday stuck on 4 hi...dealership says transfer case shift module needs replace, extensive repair to do yourself? does anyone know if aftermarket ones are worther?
thnks anyone!

Checked TCCM module, no corrosion so figured bad box. Bought and installed new TCCM box and nothing changed? Still won't go back to 2hi or even 4hi.

Under the battery there is a vaccum activated switch, looks like a big black diaphram. They are about 10 bucks at AutoZone, its worth a shot, if it has a hole in it, it will never pull the transaxle in or out. If it leaks, you will get some crazy stuff. One wheel will go in and the other will just spin, you'll get stuck in low gear with just the rear wheels, crazy stuff. I was always taught that the best way to fix any 4 wheel drive problem is in reverse. Its the lowest gear your vehicle has, and when compared to the rest it is usually in the best condtion. So here's what you do. Go to a big empty parking lot, find a nice open area, and put that blazer in R! Let it start going backwards, take it very easy on the throttle. The ideal shift speed for the transfer case is 4 mph. The blazer should actually backup and hit that speed on an idel. Press the desired 2 wheel hi mode and it should slip into it. It's funny that you guys are saying that you can't get it out of 4 wheel, most people can't get it into 4 wheel. The transfer case is supposed to fail to two wheel high, meaning if it malfunctions it is supposed to slip back into two wheel high, before it falls off the vehicle.

if the 4x4 lights keep blinking and doesnt engage to 4 hi or 4 low i would check all the vac hoses......and if you take the battery out and the battery plate under the battery you will see a rubber bladder that might have a tear in it....if thats the case replace it and the 4x4 should work fine.....i did this on my 2001 chevy blazer and it works fine now

DUDE! seriously.... just edit the last post you made and add stuff so you dont eat a whole damn page.... :icon_doh:

here since chilton and haynes manuals generally blow, take a gander at this bad boy...