4wd advice needed

[Cctbobby]

Ok so looking thru a lot of these I haven't found out my issue. Btw, brand new to the forum here and just got my 04 envoy last weekend and 4wd didn't work. Nbd it's a Chevy and they have issues... he said he took it to the dealer and code for shift motor was bad. (No idea what code tho)

Anyway, My issueis this. My switch is stuck on A4WD. However, I can spin the rear tires with ease. No front lockup. Turn the switch either direction, no change what so ever. Jack up front tire, spin it and driveshaft spins. if I pull #8 fuse it unlocks. And tire spins freely. (Actuator is good)

Also when I plug fuse back in it locks back up. All lights on switch flash on startup, if I put the switch on 2wd, 2wd flashes and I hear encoder motor shift, but right back to A4wd on the switch. Turn switch and nothing happens.... back to square one.

I replaced shift motor with new one and exact same results. If I take the motor off and move selector I can feel what appears to be 3 settings. Non of which lock up the driveshaft, it constantly spins free.(tried neutral and park in all settings)

I replaced tccm and switch with junkyard parts just for grins with no change what so ever.(luckily they let me return them) someone had replaced mine already with a doorman tccm. It is possible the junkyard one was bad but having the exact same issue as mine doesn't seem likely

So I'm dreading that it's thetransfer case. But at least it would be fixed IF THATS THE ISSUE! Wiring looks good around t-case. Someone has replaced the tan wire from motor to connector by fuse panel. But it looks fine. Haven't put a multimeter on any wires yet.

So if it's the t-case, fine I'll buy one. But since the selector shaft moves I feel like it would at least show different modes on the switch. Maybe not but can't be sure. I really don't want to put a new transfer case in and have the same issue.

 

[Sparky]

I'd try an encoder motor before the transfer case. You said you can hear it move, but, is it moving correctly is the question. But, I'd meter out that wire first before that as well.

 

[Cctbobby]

I tried a junkyard motor and then bought one new and all three do the same thing tho

 

[djthumper]

Check the fluid in the transfer case, it should be changed every 50,000 miles and be blueish in color not dark. Your disconnect fork could be the issue which would mean a rebuild of your disconnect.

 

[Cctbobby]

I have not checked fluid yet. But mainly because I was afraid of what I would find haha.ive only had the truck 5 days or so so I haven't a clue on svc history. You say disconnect? What is that

 

[djthumper]

This article should help you troubleshoot your problem. http://www.offroadtb.com/articles/tech-docs/what-is-wrong-with-my-4wd-system/

 

[Cctbobby]

Thanks, I did check that page out before I did anything. There's another one as well but they don't really cover my light (switch) issues. I was really hoping I had missed something electrical. I just don't want to buy a transfer case if I don't need one...

 

[Sparky]

That's the thing on the passenger side that the passenger CV axle goes into. It is attached to the side of the oil pan. It has a shift fork that is operated by an actuator (black, has a wire going to it) and it engages or disengages the axle from the differential. If the outer seal goes bad, it can get crud in it, that then gradually ruins the unit and causes a failure. One telltale sign of a bad disconnect is if the CV axle flops around where it attaches to it.

Personally, my first gut feeling is it isn't the case, because it should still at least try to shift modes I'd think, or if it is jammed inside it should notice it doesn't move and throw a service 4x4 light. I'm really not sure what to make of that one.

 

[Cctbobby]

It does have the service 4wd light. And with the front end lifted, if I spin the tire, the driveshaft spins with it unless I remove the #8 fuse and it unlocks and the wheel spins free

 

[Cctbobby]

Ok so new update. Had an extra set of hands today. Shift motor off, fuse out.

Started envoy had a buddy but it in neutral, I manually shifted tcase into 4lo. He put in gear and you can deffinetly tell it's in low gear, but front driveshaft still spins freely. He was in drive with foot on brake

 

[Sparky]

Front shaft will spin freely if the disconnect on the passenger side isn't engaged. Well, although maybe with it in 4LO the shaft is engaged in the tcase, so you wouldn't be able to spin it by hand in that case...

Hm, OK then. So, case failure perhaps? Did you check fluid condition/level?

 

[Cctbobby]

I didn't check fluid since the damage is likely already done... and I was kinda going on the fact that at least in four low it would be engaged in the tcase. I knew front end wasn't locked without fuse in but seemed like a good way to see if tcase would lock in. Guess I'm gonna start hunting down an transfer case in local junkyards and hope I find a good one

 

[Cctbobby]

So kind of an update. I started over with diag. Reset system (pulled #8 fuse) with truck on, not running. I can hear front axle actuator engage and encoder spin. Actuator actually locks front wheels to driveshaft so that's good. Encoder spins to 2wd,4hi, or 4lo(depending on where I put switch) switch flashes as motor turns. Motor stops when it sees it should be in gear,(but I never hear a clunk into gear from t-case) then spins back to a4wd mode and "service 4wd" light comes on. This happens no matter which position in. Now like I said. I can manually spin the slecotor shaft on t-case into low and front shaft still spins, so that's a problem. But why is my motor going to a selected gear and then back to a4wd and throwing a light? Will system go back to previous mode if it doesn't go into gear? Which would in turn cause the service light?
I really would hate to burn this truck to the ground if I put a transfer case in it and it still not work...