[Holmes2112]

Hey guys.
My truck is stuck in 4 high. I can’t seem to find anything on YouTube on how to fix it. It’s a 2003 Silverado 2500HD.
I have bought an electric actuator to replace on the T-Case. I have also heard about some Vacuum lines that could be the issue. I can’t find much on YouTube about those either, if it happens to be the problem.

 

[Tavi]

Have you tried multiple combinations? Attempting to engage 2 hi while moving forward or backwards. In park or neutral.

 

[DMAXfirefighter]

Shouldn't be any vacuum lines involved. Electric actuator/encoder motor on the transfer case, and an electric actuator on the front axle that engages it. Both use the same method of moving a shift fork and slide collar to change their mode. Can you tell if the transfer case encoder motor is moving or not? Maybe the front axle just isn't disengaging? What is your indication its still in 4wd, the light on the dash or just that you can tell when turning that its not disengaging?