Should I try unplugging this next? I pulled TCCM fuse like you suggested for about an hour yesterday and nothing still.

 

I meant for you too try that before unplugging fuse. It can't hurt to try.

 

ok, I'll try unplugging that and then the fuse and let you know what happens. Thanks for all your help so far.

 

THIS WAS POSTED BEFORE in this thread by me, just following up for more help ****(Well it didn't work for me. I checked the codes by jumping the A and J pin and it gave me a code 1 and 3. Figured resetting the TCCM would do that trick but no such luck. Checking this site... http://www.s10extremist.org/tech_art...ctronic4x4.htm it is pointing towards the encoder motor being bad. I guess I will bite the bullet and try changing that.

Edit: Before I try changing the encoder I have another question. After I reset the TCCM I could push the 4wd drive button and the lights would blink as normal but then go out. After doing this a few times the lights eventually would not come on again until I reset the TCCM again. I hear nothing under the truck and the actuator would not move at all either when the buttons are pressed. I only hear the TCCM click. Will the actuator still try to move and do something even if the encoder is potentially bad? How about if the TCCM is somehow bad? I inspected the actuator and couldn't find anything wrong with it, although it is really nasty and dirty, ha. I also checked some vacuum lines and they seem good as well. Anything else you guys would try before changing out the encoder motor? Should I try a different TCCM if I can find one? Thanks all.)***

Tried replacing the TCCM and the encoder. No dice. Still throwing a code 3. All connections are good, no wires are burnt or anything. What else could it possibly be? I am getting power at the encoder as well but it wont do anything when the switch is pressed.

Dumb question, but does the car need to be running to engage the encoder? I figured I would at least hear it turning correct? I thought it just needed to be running to create vacuum to engage the front wheels.

Any other things I can try before I blow this thing up? Also, I was able to take back all the parts so I'm not out any money yet. Thanks guys.

 

Have you done a continuity/resistance test on the wiring between the switch, TCCM, and encoder?

Are you using new parts? If so, maybe you have received a faulty component.

 

TCCM was not new but the encoder was.

Only testing I have done is test the power at the encoder motor harness and all was good.

 

So you didn't read through the RSGear.com article linked to from the first link I posted above? That is a very good article on diagnosing the NV233 transfer case. Gives the values for each position of the encoder motor, etc. If all you have done is verified power, that is really just the beginning.

 

Hey Recon, your situation sounds just like mine. I'm getting absolutely "nothing" when I push the 4WD button, not even a "click" or a flashing light by the 4WD button.
4WD worked fine last Winter. Then sometime in the Spring, one time all of a sudden, it switched into 4-Lo by itself. I had a hell of a time getting it out, back into 2WD. So I disconnected the Switch in the dash by pulling it out and disconnecting the wire in the back. Then around November 1st, I reconnected the Switch. I have a green light lit up next to the 2WD switch, but when I pushed the 4WD button, I got "nothing". I did find that the 4WD fuse in the fuse box at the left end of the dashboard was a bit "kinky" so I replaced it. But all that did was make the green light next to teh 2WD button brighter. Still "nothing". I don't know what the "TCCM" fuse is, yet, but I'll look for it.
So this seems like it is Electrical to me, the problem is what? There are so many possibilities, most all of them very expensive.
After I played around with it, tonight 12/7/10, my Service Engine Soon (SES) light came on at 9 pm. I had 2 codes P0740 and P1860. I went to www.troublecodes.net (as suggested by this Adminstrator in another Thread), and found that...

P0740 TCC Circuit Malfunction (where "TCC" apparently means Torque Converter Clutch. Not sure what that is yet).

P1860 TCC PWM Solenoid Circuit Electrical/Transmission Transfer Case Contact Plate "D" Short Circuit to Battery..... Whatever the hell that all means.

Now, I don't whether or not thes 2 Codes appeared cuz I was messing around with the 4WD and pulling fuses while the car was running or what?

I'm not very good at Electrical, so I don't really know how to check electrical stuff.

I did have trouble with 4WD a couple of years ago. I reached up under the dash, grabbed a bundle of wires, and jiggled them. Then the 4WD worked.... for awhile... so I don't know if a short in a wire under the dash. I'll have to pull the dash covering, and try to look, and try to check the Module too.

Recon and kewlbear...... Ahhhh Ha!!! Maybe that is my problem too!!! To unplug this TCCM (whatever and wherever that is, and how to unplug it), to "reset" it. To clean off the connectors (as this Administrator had suggested in another Thread).
Cuz, I am getting "nothing". I had trouble with it not working 1-2 Winters ago. I discovered the end of one vacuum hose was disconnected. Then it worked fine, last Winter. I don't believe that I have put ANY money into the 4WD at all. I'd have to check my file. Not even for a New Switch in Dash, cuz I think Dealer said it costs like $70+ (for a $15 part). Plus, I don't think that that could be the problem, cuz that switch is so simple. So I don't recall spending any money on it. Just alot of time and pain in the ***.
But I will try as you suggest. I'm thinking that this TCCM is the Transfer Case Contol Module, and that it is located either behind the dash, in the center, or behind the glove compartment. That it is the thing that "clicks" when you push the buttons. If so, then I think mine is behind the glove compartment.
If that is not the problem, I am thinking there is a short somewhere along the way, or a bad fuse I don't know about. I had removed two fuse, ABS and DRL, cuz ABS Brakes suck and are dangerous, and having your headlights on in the daytime is retarded. But I know that stupid GM loves to "link" things together to unrelated things, to prevent YOU from doing stuff. Like when I took out the DRL fuse, one of my highbeams will not go on. That is to prevent you from removing the DRL fuse, cuz they want you to have your headlights on all the time in the daytime, to drive other drivers crazy, and to burn out your headlights sooner so you will have to go to the dealer to buy a new overpriced one. Also, cuz the Univ of Michigan (or someplace) did a study like 30 years ago, and liked what Canada does, and determined that having your headlights on in the day time is safer!!!! Go figure!!!.
So GM loves to connect unrelated things together just to mess you up.

But, I will try to unplug this TCCM, clean connectors, leave it unplugged for awhile, and disconnect the battery, then reconnect it to "reset" it, I hope.
I mean, I know that it is something either "stupid" or "major" (like the Electronic Switch on the Transfer Case). If it is something "major", then I'm screwed, cuz there is nothing I can do about it. It'd cost more to fix it than this piece of junk 1998 Blazer with 225,000 miles on it is worth. I don't even think it is worth $500.

Longer02.........I doubt that it could be the Vacuum Actuator under the battery. Cuz that is a very basic and simple mechanical device. Unless it is rusted solid, and the pin/arm won't move in and out, or there is a rip in the rubber covering, there isn't much that can go wrong with it.
Maybe you should try to disconnect the battery, unplug the Module, clean the connectors, wait awhile, several minutes, then reconnect the Module, and reconnect the battery. That is what I am going to try to do, as soon as I can. See if that does it for you. Also, check all associated fuses. You may need to makes inquires in here as to what all of them are. I know of 1, maybe 2, and I think someone mentioned another fuse... a TCCM fuse, wherever that is I don't know, yet????
Good Luck.. I know I'll need alot of luck. What a pain in the ***!!!. But with out 4WD my Blazer can't do jack in the snow. With it, it can go thru anything.

Thanks Everyone..... I wrote down alot of notes on what everyone suggested to try to do. But it is 12:35 am now, so can't do anything now. But as soon as I can, I will try going thru all the unplugging, reconnecting scenario. Thanks. I hope it works, cuz I know it is something stupid, something electrical. In module or a short.

But wish I knew how to do this continuity/resistance test on wiring from switch to TCCM, to encoder. I'm not very good at electrical. I have a handheld tester thing, if it still works, I'm sure it needs batteries. But I reallly don't know how to use it, what setting to put the dial on, what the numbers mean, etc..

 

I have a similar problem on my 99 blazer i have the auto 4wd transfer case with the 4-button switch on the dash. My problem was every light on my switch lit up at the same time (even the red neutral light) and it gave me no response when trying to engage 4wd. I replaced the 4-button switch with a used one and it worked for for a while until i decided to go get it stuck in 4lo haha sound familiar? I got it out of 4lo eventually manually and took apart the encoder motor ( i know ur not supposed to but it was worth a try because it was corroded and seized) to realign it out of 4lo. After i got it back into 2hi my new/used switch has all lights lit up again and no response to anything. I don't know if something is shorting out my switch or a bad encoder motor. I gave up and toughed it out in 2wd last winter.

This year i've decided to get the 4wd working again, so i replaced the encoder motor with a good used one. I'm pretty sure it was good because a buddy replaced his motor and it didnt fix his 4wd problem until he replaced something else, not sure what it was (he kept the new motor in and gave me the used one). I will try and unplug the TCCM on mine and see if that will fix it. Otherwise i guess i will try and buy a new switch again seeing how that fixed it the first time until i got it in 4lo last season. Hopefully i don't have something shorting my switch out and my money goes down the drain on a new switch.

 

OK, everybody, I finally got a chance to work on my 4WD, today, Sat 12/18 (still am, technically, as I have the Module out and right here).

1998 Blazer.

I disconnected the Battery, + and -; I disconnected the electrical connection to the Electronic Motor on the Transfer Case under the car; I thought the 4WD Module was behind the glove compartment, but it wasn't. Then I found this "box" under the center of the dash, down low. It had 3 different wire connections, so I disconnected all 3. I looked under the dash, under the steering column, but I couldn't find any "TCCM Fuse" as people in here stated would be.; ...... I didn't find any Fuse Box under the steering column, as people has said in here. But I checked any connections and fuses (elsewhere) I could find or think off.; ......... I let everything sit for like 45 mins while I took a break. Then I put everything back together, and took it for a test drive.

oh yeah, I turned the key to "ON", the lights on the 4WD Switch flashed for awhile, then went out. I turned the key to "OFF".. I did this 6 times.

When I pushed the "4HI" button, it went into 4WD, yeah!! But, then when I pushed the "2WD" button, it WOULD NOT go back into 2WD.. uh oh!!! I kept trying. At one point, the "4HI" light went out, but the "2WD" light DID NOT go on!!! So I kept trying. Finally, I think I put it into NEUTRAL, pushed the "2WD" button, and it went back into 2WD.
So, I thought, that's not a big deal. But when I pushed the "4HI" button again... NOTHING!! Not even any "clicking" from the Module. So, it appears that it did in fact come out of 4WD and go into 2WD cuz I can tell if I turn the wheel tight to make a turn, going slowly. If it is in 4WD then it "binds" and "shakes". If it is in 2WD, then it doesn't and I can turn the wheel tight, and touch the gas, no problems.
So I parked, and put in in NEUTRAL. Then I pushed the "4HI" button. This time the "4LO" light flashed, and I heard "clicking" in teh Module (which sounded like it was coming from behind the glove compartment). So I looked again, and this time I removed a small covering just under the glove compartment. But no Module???? I kept pushing the button and hearing the "clicking"... Grrrrrrr!!!!... Then I thought, "oh, maybe it is in the Side Panel".. So I took the side covering off, and there the little sucker was!!!! Smaller than I thought, with one Electrical connections. So I unscrewed it (battery disconnected again), and disconnected the wire. Brought it into the house. It looks good.

So, Now I have to go reconnect it, reconnect the battery, do that turning the key to "ON" 5-6 times, and trying to see if the 4WD will work now. I dunno.

So, any more Ideas?

Could it be a faulty 4WD Switch (the buttons you push) in the dash? I checked the fuse to that, and it looked ok.

Where is this "TCCM Fuse"? What does it look like?
I have a small fuse in the large fuse box under the hood, that is called "ACT", I think or something like that. Begins with an "A" anyways. My book says it has something to do with 4WD.

Ok, I'm off now, to put this Module back in. It is 9pm, Sat 12/18, and it is dark and cold out there. No Garage!!!

Wish me Luck!!!

Todd - Boston.