Hello, so we've been having a whole lot of trouble with our 4wd in our 2003 Suburban. Initially, it was stuck in 2wd, but we replaced almost every part we could in the 4wd system besides the transfer case because we think that part is ok.

The last part we put in was the transfer case actuator motor, and initially, it was working finally. So it changed into and out of 4wd when we weren't moving. Then we went to test it out, so we drove to the bottom of a hill, went into 4wd high to go up the hill, but then at the top we tried to switch into 4wd low, but then it got stuck in neutral, and we rolled down the hill and had to get towed.

Today we replaced the transfer case fluid in hopes of an easy fix today, but nothing happened. So what's up? Does anyone know? Thank you!

 

Full scan of all 4 code families is needed to see what codes are being recorded. Drivetrain codes may not show up in the P codes, need the B, C and U codes read also. Codes help narrow down the diagnostics.