*SOLVED* no 4x4, no lights, no nothing!

[tarsh]

Ok.so, I said it fixed itself but planned on stone snow wheeling for my little brothers birthday and it wouldn't go into 4hi again. Instead it would switch to a4wd automatically . Tryed 4lo and it worked . Then I switched it to 4hi and BOOM! No lights amd service 4wheel drive light came on. My question ... TCCM? If so, would one from an envoy work? Appreciate it

[The Roadie]

Check fuses first. 2003+ TCCM from Envoy will indeed work.

[tarsh]

It started working again this morning and now it stopped working again so I doubt it's a fuse but I will check them

[tarsh]

Thanks roadie.fyi I just read your post on trailvoy about your bridging ladders . How duo you like them?

[tarsh]

Ok guys. Iv replaced the TCCM which fixed the service 4 wheel drive light. Everything appeared to be working properly. Said I was in 4hi, lo,a4wd but it wasn't. Both the encoder motor and the actuater work. I followed James's schematic on diagnosing the 4 wheel drive system. I have a backround with 4 wheel drive so we did some diagnosing of our own. I pulled the actuator and engaged 4 wheel, seemed to be working fine... I even used an extension instead of the actuater to engage the 4 wheel. So the disconnect also seems to be working properly. Then I pulled the encoder of the t-case and opened it up to see if it was messed up.

All appeared well. I ultimately had to open it up because the splines didn't line up with the t-case because I engaged 4hi with the encoder off and the service 4 wheel system came on and I couldn't spin the encoder anymore to line it back up. So my question to you guys, if in park, with 4 wheel engaged should the front prop shaft spin? I belive it souldnt but my brothers say otherwise. If it is spinning it would be the t-case blown right?

[Diacom]

Nathan, for the sake of cleanliness, please use the same original post for your updates. There is no need to create a new post each time you want to update. This just spreads the information across several posts rather than having it inclusive and easy for others to search.

I'm sure a Mod can combine these so they are all together for you.

[tarsh]

My bad. I actually ment to do that.

[The Roadie]

So my question to you guys, if in park, with 4 wheel engaged should the front prop shaft spin? I belive it souldnt but my brothers say otherwise. If it is spinning it would be the t-case blown right?

The clutches in the TC should prevent the driveshaft from spinning. Are these non-mechanical brothers?

[tarsh]

No. All of is a mechanicaly inclined. We have a lifted something:-) so what ur sayn is the clutch in the TC could be fried?

[Wahugg]

I could be wrong here but...

If both front wheels are on the ground with 4x4 engaged (disconnect connected) shouldn't the drive shaft not move irregardless of the clutches being fried? If it is spinning in the scenerio I just described, then I bet your disconnect isn't engaging and that you also have bad clutches.

-Wahugg

[tarsh]

Hmmm. I didn't take the disconnect off and inspect it. But there was a noticeable difference when I manually pushed the "pin" that the actuater pushes to engage 4x4. I think I'm going to drain the TC looking for metel shards or nasty fluid. The only thing that gets me is I wasnt goin but 5 to 10mph. Then some grinding happened . Sounded more like skipping, from the TC.

[navigator]

I'm thinking if your prop shaft (front drive shaft) is turning when you are in park that would lead me to xfercase issues or at least something telling the xfercase to engage.

[dvanbramer88]

[The Roadie]

No. All of is a mechanicaly inclined. We have a lifted something:-) so what ur sayn is the clutch in the TC could be fried?

"Inclined" doesn't mean they're read the Tech Article here on the internal design and theory of operation of the NP226. That's required reading. There are clutches, gears, a chain, and lotsa splines inside that puppy. I previously said the clutch could be fried, yes. Could be worse internal carnage.

[Wahugg]

Well think about it, A differential consists of 3 inputs/outputs. In order for one to move, another has to move as well but not the third. Think about a open diff with one tire in the air. The drive-shaft and the wheel in the air will turn, but the wheel on the ground will not.

So now that we have established that at least 2 out of the 3 inputs/outs have to be moving, lets apply it to your situation (and we are totally ignoring the transfer-case right now).

I am assuming that you have the vehicle on the ground and that you have engaged 4x4 (disconnect engaged). This would mean that 2 of the 3 inputs/outputs are NOT moving. This means that your drive shaft (the third input/output) should in no way rotate. Why? If it is rotating that means that one of the wheels should also be rotating and we know this not to be true as they are on the ground. The only way the drive shaft can rotate then is if the disconnect is not engaging, allowing for the intermediate shaft to turn as if the wheel were indeed off the ground.

Therefore we can conclude that your disconnect is not engaging and needs repair.

Now even if the disconnect was broken, the prop shaft should still not turn because of the resistance from the clutches in the TC being engaged (assuming you are in 4 HI or 4 LO).

Therefore we can also conclude that your TC is either not engaging due to you not engaging it all the way, or the clutches being burnt so they are unable to engage.

-Wahugg

[tarsh]

Wahugg. U my friend are a very intelligent man. Hopefully just the disconnect is messed. Let me get it off and opened up and see what's up.I'll post back up. Thanks for your help guys. I was about to buy a new TC.

[navigator]

I think what Wallace is telling you is that in addition to your xrfercase issues you likely have a problem with the disconnect as well.

Have you checked your fluid yet? I'm sure as long as you have been a member you have seen Roadie harp on the fact that the fluid needs changing every 50k miles and that neglect will wreak major havoc on the xfercase.

[tarsh]

I have not yet. Nor has it been that I know of. It's got 156000 on it too... I'm in for a treat I think

[Wahugg]

What I am trying to say is that your disconnect is more than likely worn out. If the motor that engages the disconnect was not working properly it *should* trip an 'Service 4 wheel drive' light. Since that's not happening and we have a huge track record that points to the actual disconnect being worn.

I'm personally not writing off your transfer-case yet. I think that you had a problem with your TCCM which was never fully fixed, and that perhaps you might not have manually shifted the T-Case into 4x4 properly. Remember, it MUST be in 4hi or 4lo. If in Auto 4x4 than the clutch will NOT engage enough to provide resistance to the drive shaft.

-Wahugg

EDIT:

After re-reading through the thread two things poped out to me.

First, you said you replaced the TCCM.... were did you get it from? New? Dorman or OEM? Used? Off of what gmt360?
If it was a new OEM unit, did you have it reprogrammed? If it was used, did you get it off a GMT360 that had the same 4x4 system? ie(4hi,4lo,A4wd vs AWD)

Also, you may have misaligned something while you had the TCCM off messing around with the T-Case.

[tarsh]

I do not use a4wd at all. O won't get a chance to break down my disconnect till the weekend. Those don't have a rebuild kit right?