Bad Transfer Case or Tranny? (Answer: High-Low Sleeve in TC)

2012 Crewmax Platinum 4x4, 158k miles
I use 4x4 a couple times a year for hunting and whatnot. Changed TC fluid at 150k.

So I just finished pulling a loose tree root out yesterday. The truck took a couple tries to go into 4LO, but it went. The root was loose and came out easily.

I then backed up slightly to slack the rope, stopped, shifted into neutral, and turned the selector to 4HI. Nothing was happening, So I put the truck in reverse to trigger it and it started making grinding/slipping noises. I quickly popped it back to neutral and it was still grinding but less until the spinning stopped.

I had to backup to get out so I shut the engine off, shifted into neutral, and my son helped me push it back.

I restarted the engine and went quickly to Drive. No grinding. Slowly drove out to road and selected 2HI. It went into 2HI, so I slowly drove back to park somewhere easily accessible. If I tried to speed up or slow down there was clunking, but it would drive forward. When I stopped I tried reverse again....grinding and no movement. Slight grinding in neutral while spinning down. Shifted into Park and shutdown. No grinding in Park.
D7 Xtool Code P0500 (and 1201 I believe). The ECM/second code piggybacked off the first I think. Check Engine Light, Trac Off, and flashing 4LO popped up while driving in 2HI

So....does this sound like a TC rebuild or tranny problem? I suspect TC but can't find similar symptoms while searching the web and forums. I can pull the TC out myself, but I'm not doing the tranny. Local mechanic quoted $6700 for new Toyota TC replacement install. I chuckled and moved on to searching a rebuild kit or reputable TC shop in Phoenix.

I appreciate any input!

 

Lack of responses forced me to do some more research.

Referencing timestamp of 8:22 of this incredibly useful video I found in another thread....

(599) Center Differential Transfer Cases - YouTube

...I think my HI-Low shift sleeve is barely engaged in Drive but pops out going into Reverse or Neutral. With grinding noises in Reverse and less grinding in Neutral, my 4LO actuator probably isn't timed correctly anymore. I may try to fix that first before tearing the entire TC apart. I won't be able to diagnose for a few days but I'll post any updates.

That is a great video dissecting power distribution from normal transfer cases and center differential/locking transfer cases. Everyone should probably bookmark it if you haven't already.

Cheers,
Dewey

 

Youtube is mostly your friend. A C1201 code is an accompanying code, much like a catch 22. I've had that code for years and haven't really figured out what it is, but it does come and go, no issues with drivability no other codes accompany it.. On the other stuff, I'm 2wd, so I'm no help there

 

Most likely the TC shift actuator not fully allowing a shift. When I rebuilt my actuator and was timing the gearbox to the shift shaft, I'd occasionally get that horrible grinding.

 

I was able to troubleshoot the issue. I firmly believe that the issue is the High-Low sleeve inside the transfer case.

Reference photos. The actuator looks just fine. I was able to slide the rod/sleeve back into Low position with the transmission in neutral. Then I went for a drive around the block (with the actuator removed) in essentially 2wd low. It drove fine. No grinding and Reverse worked as normal.



I then attempted to push the rod all the way forward to the High position. I can't push it past the 5th tooth. The YT videos show approximately the 4th tooth aligned with the bushing, so I don't believe it's going all the way forward. I reinstalled and retimed the actuator so that it would push the rod forward slightly. It will drive forward just fine (I didn't go faster than 7mph) but it still grinds in Reverse and Neutral.



So....yeah pretty certain it's the High-Low sleeve since I can't even push it all the way forward by hand.

Sidenote - my actuator doesn't have a position switch. I also noticed it is also missing one electronic pin at the plug. I did clock it forward and it timed itself to the normal position with the key on, so this appears normal.



Anyone crack open the TC on here for a rebuild, or do most people just replace them?

Cheers,
Dewey