posz71

So recently all of my 4x4 lights on my selector switch have been on and my transmission tries to take off in 4th gear unless I manually shift through the gears. It will randomly flash service 4x4 once and the selector switch will go to 2wd then starts shifting fine. Before any of these problems I put a used read end in it that had 3.42 gears while the front diff still has the factory 3.73 I knew better than to try to put it in 4x4 and it did fine except for my speedometer being off. I have since installed 3.73 gears back in the rear diff but the problems still occur. Any advice would be much appreciated! I've already checked 4x4 fuse and grounds which leads me to believe it could be my transfer case control module or speed sensor? Just haven't read anywhere of anybody having the same problems I'm having

Wolftrk99

iTrader: (5)

What year truck?

posz71

99 z71 4l60

Wolftrk99

iTrader: (5)

Do you have any codes stored? Have seen bad 4wd switches and encoder motors cause similar issues with the 4wd/tccm.

posz71

I just went up to autozone and their code reader says it's got a P1875 error code

posz71

Says 4WD low switch circuit fault

Wolftrk99

iTrader: (5)

I dont have the diag/flow chart in front of me, but quick search leads to a few different issues it can be; chafed or broken wires, water intrusion in a connector, faulty switch, faulty tccm, faulty encoder motor...