hey guys, I got a problem with my 4x4 right now.
I have a 98 4x4 blazer automatic.
ive been messin with it a while now but heres where im at..
I press the 4hi or 4lo button, (3 button switch by the way), and I just get a click.

so I took the harness off the back of the computer in passenger kick panel, cleaned terminals and then when I press the 4hi or 4lo it flashes and I will hear about 3 clicks (cycles) in the computer in the kick panel.

reason I say this, is after about 3 attempts it will go back to the single click, and I clean it again and it cycles again..

now heres the problem, the 4x4 does not work either way, whether its cycling or just clicking.

so I been messing with the vacuum, I have solid vacuum going to the transfer case switch at all times. but when I press the button, I do not get vacuum sent out to the actuator located under the battery tray.

I replaced the transfer case switch and still no vacuum coming out.

I thought maybe the encoder motor wasn't getting signal so I cleaned the harness on it good, still nothing.
so I nutted up and bought the $150 encoder motor put it in, and still nothing...

So what I need to know guys is this:
Can you hear the electric encoder motor engage when you press the button?
Can I lay next to it, have someone press the button and be able to hear it?

If so I cannot hear mine engage.

Is my 4x4 computer bad?
Can I test anything?

let me know guys thanks

 

Yes you can hear it, but are you listening after you reset the module when its doing it's three click thing or after you have been punching the button a few times.


Also how are you testing the vacuum to the actuator.


The module can be re-set by disconnecting the battery for half an hour. You don't want to damage the connectors on the module, there not that easy to find.

 

When you pulled the encoder motor off, did you try and shift it manually? If the encoder motor isn't shifting the T/C, the vacuum switch wont be activated. Could be the TCCM.

 

Spittybays:

I tried listening to it both ways, cycling and clicking and don't hear nothing.

I tested the transfer case switch 2 ways:
First I Pulled the battery and battery tray out, got the engine running, took the vac line off back of the actuator and had someone pressing the button.

I didn't feel anything, so figured maybe that line has a hole in it or something.

So I unplugged the vac line going to the actuator off the transfer case switch itself, put my finger over the hole and had someone pressing it.

Still didn't feel nothing..

Diaita:

No I did not try to shift it manually when I had it out. Not quite sure how to do that.

But when I put it in, I had to turn it with the gears met up to get the bolt holes to line up. It moved with a little drag on it. sounded and felt like if you where spinning an rc cars tires with it shut off.

You guys know if I can poke a multimeter around my encoder motor harness terminals, have someone press the button and see if im getting signal sent through the right pins?

What are the odds of the brand new encoder motor I bought being faulty?

Thanks again boys

 

It's possible, but in your first post you mentioned that cleaning the terminals at the TCCM seemed to make a difference. I'd take another, (closer) look at the pins & sockets in the connector.

 

Proly just gonna buy a new tccm guys, Ill let yall know.

 

Hey Black, why don't you give one more shot to what Capt. had to say.
For about $7 you can get a can marine electronics contact cleaner and spray the crap out of the module contacts and any plugs to the motor also the dash switch.
Just an idea.
For me 90% of the time that can fix a whole bunch of stuff.

 

Ill give her a try.

Wouldn't you think its the tccm though if that doesn't work?

I put a new dash switch in a while back because the clips where broke off my old one.

Have solid vacuum to transfer case.

New t-case switch.

New encoder motor.

The tccm is $140. sucks but ill proly get it if cleaning don't work.

Ill have her forever anyways, chevy runs deep boys

 

It would suck to plug it in and have it still not work then still have to check all the wires for continuity. Are there any places that will except returns on the unit. If so then just buy it.