Gotta to rent a vacuum pump from your local auto parts store to properly troubleshoot .. they are normally free to use.. it could be your IWE solenoid or your T-case shift motor.. from what you state. you would know if your in 4 lo for sure ... if its shifting into 4wd i would look at your solenoid..
08 FX4... Flowmaster Exhaust, line-X, Sky Jacker leveling kit. 295/65/20 Nitto trails mounted on 20 X 9 Carol Shelby wheels. AIRAID CAI. Projector/Halo headlamps and LED Tails & 3rd brake lights,custom upper and lower Grill. Edge Evolution. Interior/Exterior LED lighting, NFAB step bars.