Transfer Case Issue

Postmark

TYF Newbie
Joined
Sep 21, 2021
Posts
12
Reaction score
1
I have a '99 Tahoe that won't move, it's almost like the transfer case is locked up. I pulled the driveshafts, everything turns. I pulled the encoder motor off, I was able to shift the case manually with no problems, and front axle is free in 2HI. I put another encoder motor on that i had laying around, and with the ignition on and engine off, everything seemed to be ok. However, once I started the engine I was right back to things acting like they're locked up. TCCM bad? First time with one of these.
 

east302

Full Access Member
Joined
Dec 21, 2016
Posts
1,042
Reaction score
540
Location
Mississippi
Does it move in 2H? If so, do you know the history of the truck? Could someone have swapped the rear differential (or front for that matter) and mismatched the ratio?
 

Postmark

TYF Newbie
Joined
Sep 21, 2021
Posts
12
Reaction score
1
It does not move in 2H, 4H,4L, or neutral. I don't know the history, the previous owner said it stopped moving and he had to have it towed. It seems like the TCCM is telling the encoder to stay in between modes and binding things up.
 

east302

Full Access Member
Joined
Dec 21, 2016
Posts
1,042
Reaction score
540
Location
Mississippi
Just to rule out a brake issue, will any tires turn when jacked up and in neutral, engine off?

It sounds like you have the NV243 case (pushbutton 2H, 4H, 4L but no Auto). Do you have a good scanner (Tech2 or similar) to check for any transfer case codes? Does it complete the shift and the appropriate button light stays lit?

The TCCM should be under the dash and pretty accessible. A junkyard swap probably wouldn’t be the worst thing to try.



You must be logged in to see this image or video!
 

Postmark

TYF Newbie
Joined
Sep 21, 2021
Posts
12
Reaction score
1
It's the 246. Not a brake issue. Key on, engine off, everything seemed to be ok after I swapped the encoder motor. Once I started the engine, it locked up everything again.
 

George B

Oh what fun...
Joined
Feb 5, 2020
Posts
4,242
Reaction score
8,758
Location
Wisconsin
Does it just rev like its in neutral? Of is it locked up as in it won’t roll?
 

swathdiver

Full Access Member
Joined
May 18, 2017
Posts
13,885
Reaction score
15,234
Location
Treasure Coast, Florida
I have a '99 Tahoe that won't move, it's almost like the transfer case is locked up. I pulled the driveshafts, everything turns. I pulled the encoder motor off, I was able to shift the case manually with no problems, and front axle is free in 2HI. I put another encoder motor on that i had laying around, and with the ignition on and engine off, everything seemed to be ok. However, once I started the engine I was right back to things acting like they're locked up. TCCM bad? First time with one of these.
Be nice to know the internal trouble codes so you're not guessing.
 

exp500

Full Access Member
Joined
May 14, 2017
Posts
1,140
Reaction score
829
Jack it up, remove Tcase shifter motor, shift tcase manually thru all modes and verify by axles. Possibly stuck between on shift.
 

Postmark

TYF Newbie
Joined
Sep 21, 2021
Posts
12
Reaction score
1
Jack it up, remove Tcase shifter motor, shift tcase manually thru all modes and verify by axles. Possibly stuck between on shift.
I've done that. As soon as I start the truck, it reverts to being stuck in between.
 

Forum statistics

Threads
114,490
Posts
1,561,043
Members
73,156
Latest member
Giovanell88
Top