Possible 4:1 BW Transfer Case Issue

[napalmsticks]

Not too sure if everything is related so I will start from the beginning. Sorry for the wall of text...

Went down a pretty wet and muddy trail the other day in 4 high lock, didn't seem to be any issues. After this romp a couple days ago while driving to work the ABS fail and traction control fail message comes up on the display. I get to a red light come to a complete stop and it went away. Took the front passenger wheel off as something sounds like it is rubbing, everything looks good and I put everything back together.

I noticed around the same time my front prop shaft CV was spitting grease and decided today while waiting for my new drive-shaft I would remove the shaft and drive in 4 hi lock. I clicked it over to 4 hi lock in the driveway and removed the front shaft. After removal I back out of the driveway and start driving around the block to check everything out. I got about two blocks and the truck quit moving. The front output from the transfer case was spinning but doesn't seem to be locked with the rear. I threw it in park, put the brake on, get out, and spin the front output by hand, not locked. Get strapped back to the house and put the case back in 4 hi open. While I put the drive-shaft back in with the TC open it was locking with a pronounced click. The front output shaft would quit moving. I click it over to neutral and let it roll to attempt to get the holes lined up with the shaft and it will unlock followed by it re-locking when I move the output shaft by hand.

Also during this whole debacle I lost my fuel level sensor. Low fuel came up in the display with needle on E, turn the key off and back on fuel level is back.

Anyone have any thoughts?

 

[napalmsticks]

Also, after re-installing the front shaft 4 hi lock and 4 low lock seem to work. The transfer case seems to shift normally. I will jack up the truck tomorrow to verify the transfer case locks. Fluid changed approximately 25,000 to 30,000 miles ago.

 

[06 H3]

Yea Jack it up tomorrow. All 4 tires in the air...4 hi unlocked, put it in Drive you should be able to stop the wheels. Try again in 4hi lock you shouldn't be able to stop a wheel because it's locked through the t case. If your diffs are open get another person so one can grab one front while you grab the other front

 

[napalmsticks]

I'm really hoping encoder motor if anything. What is really weird to me is the output seems to lock in 4 hi open but not 4 hi lock. Really weird...

 

[CaseyS]

Possibly your shift fork. Mine did the same to me once before I cracked it and replaced the fork.

 

[alrock]

I'm with Casey s on this one

 

[napalmsticks]

Well I'm gonna be busy if that is the case, my to do list keeps growing:

-Replace cylinder head
-Replace shift fork
-Replace front prop shaft

 

[4speedfunk]

As always...multiple electronic failures at once, (ABS, fuel gauge, encoder) points to voltage problems. Check the battery & cables first...especially the ground.
Perhaps your "wet and muddy romp" shook something loose?

 

[napalmsticks]

As always...multiple electronic failures at once, (ABS, fuel gauge, encoder) points to voltage problems. Check the battery & cables first...especially the ground.
Perhaps your "wet and muddy romp" shook something loose?

I got under the truck and disconnected and re-seated the transfer case plug. I will check the battery connections when I get home today, I do have the original battery clamps... I might check the BCM and ECU connections also. Ordered the $16 shift fork just in case.

 

[napalmsticks]

The sole function of the plastic shift fork is to lock the transfer case outputs right? From what I am seeing there seems to be a second shift fork that is used to transfer from high to low gearing. If I do tear into it anything else I should replace while I have it open?

 

[4speedfunk]

Yes. You are correct...two forks. Replace the chain if you have more than 40K on it. They stretch relatively early and don't seem to have the lifespan of the rest of the parts. Fluid fluid fluid. That seems to be the key to making them last. I've had several of these cases apart, and I preach the 20K fluid change. This is a crazy short time compared to other t-cases but, the used fluid is often burnt, dark, and filled with microscopic debris. Changing fluid is much easier than pulling and rebuilding.

I would definitely check your electrical issues first. Pulling the t-case and replacing the chain & fork is not that big of a deal...but, it would suck to do all that only to find the problem was elsewhere. When my t-case bit the dust...it was pretty obvious that the problem was a mechanical part inside the t-case. It was clunking, popping, and downright broken...no question. But your issue could just be something electrical.

 

[napalmsticks]

Jacked up the truck. It seemed like at first it was locked but as soon as I went to 4 hi locked the transfer case unlocked and would not lock back up. I could stop both rear tires or both front tires in open, hi locked and low locked with the truck in drive. ABS failure and service stability system came on while testing. 4 low engages, the rear locker engages, and the transfer case sounds like it is trying to lock the front and rear together.

Would the ABS failure and stability system warning illuminate if the truck senses that the transfer case should be locked but both front or both rear wheels have stopped rotating?

 

[napalmsticks]

Well then...

:mock:

 

[JPaul]

That's a bummer. But hey, now you can fix it with the aluminum fork and give it a good once over.

 

[4speedfunk]

Hell yes...that's actually a good thing! You found the problem. Simple and cheap fix.
While u have it apart...clean the magnet and also the pick-up screen for the fluid pump. These are commonly loaded with particulate.

 

[alrock]

Impressed on how quickly you tackled this job!

 

[napalmsticks]

Impressed on how quickly you tackled this job!

Thanks, it was more simple than I had expected.

 

[napalmsticks]

New fork has a pretty rough surface from casting. Any need for polishing in the spots where there will be contact?

 

[JPaul]

New fork has a pretty rough surface from casting. Any need for polishing in the spots where there will be contact?

I'd say go for it, it's what I'd do.

Sent from my SM-N910T using Tapatalk

 

[napalmsticks]

Done and it works like a charm. I wonder how long it hasn't been locking for as the only reason I found out it wasn't working is because I took the front drive-shaft off, kinda surprised I never got stuck without it locking. Thanks for the help guys!

 

[Hopkins86]

Why would my transfer case clunk it's not my universal joints cuz I changed them my front yolk seems to have some play in it

 

[alrock]

There's always some slop in the GM drivetrains You said you changed the universal joint, what about the CV at the rear end of the front prop shaft?

 

[Hopkins86]

Is there a better t case I can put in this maybe a upgrade kit and does anyone know of a manual transmission that I could put in my rig