99 Tahoe stuck in 4wd. Please help!!!

[CaptainChad]

This is a square body tahoe with a new motor (5.7) and a new transmission from a 2001 tahoe. I had to fabricate some things for the torque converter to get the tranny in properly.

The truck is stuck in 4wd hi. It will go to 4wd low but it will not go into 2wd. I've replaced the TCCM, the transfer case shifter motor, speed senors, front axle 4wd actuator, the dash selector, and checked all fuses. No check engine codes.

I did talk to a mechanic who specializes in Chevy trucks, he did mention that sometimes there's and issue with the ignition and engaging/disengaging 4wd.

NOTHING seems to work. Im wondering if the newer generation tanny might have something to do with it, idk?

PLEASE help!!!!

 

[Miami-Dade]

@CaptainChad Moved you here from 2021+section.
Welcome from Miami!

 

[exp500]

Unbolt the encoder motor from tcase, attach ground wire alligator clips to ground encoder. (mark or remember original renoved position). Attempt to switch positions using dash switch. Try all switch positions testing encoder. If all work, then try manually shifting tcase where you unbolted encoder. If that works, reinstall encoder.( encoder should return to 2wd as Home, so Tcase position should match encoder Home posiition on install)
Alot of combinations of what may not work, but that will point in direction to troubleshoot further. Post your results of above testing and we will help from there. Also, GMT 400 manual has great troubleshooting guides.

 

[CaptainChad]

FIXED! I came up on a post from another guy with the same issue. I had recently done a tranny swap and had the 6 pin wiring harness mixed up so i went under and switched them out to match the wire colors and boom.... shifts in and out of 4wd smoothly!!!