Ok, my 4x4 is not engaging. I have narrowed it to down the vacuum seliniods by the battery. I gave 20psi coming from the the engine. I took the lines off the seliniods I hooked up a jumper hose and the shift fork on the transfer case is moving in and out properly. I checked the voltage at the seliniods. It read 13-14.5 volts between on and off. seems like the voltage should change? so are my seliniods bad? Or is it another problem? Thanks.

 

First your not reading PSI,
It's inches of water or mercury , a term of measurement for vacuum.
If the firewall solenoid is not operating to pass engine vacuum, likely the transfer case motor or the harness wiring is faulty.
The signal to operate comes through that path from the GEM module after the case motor has run to it's first position.
Good luck.

 

Ok, where and how do I check the case motor? I can hear it click with the switch

 

The click you hear is the relay in the dash operating to supply power to the transfer case motor.
That motor is located on the back end of the transmission/transfer case .
It turns an internal shaft to engage the transfer case to the transmission so the front drive shaft is powered.
Good luck.