ok as winter is approaching i figured i try out my 4wd.... it doesnt work! i got a 98 4.6l f150.... when i put it into 4wd the 4x4 light comes on and it clicks like its going into 4wd but the front tires dont spin..... even in 4lo. HELP ME PLEASE

 

Lift and support the front so the tires are off the ground. Key on engine off engage 4Hi and try to turn the front drive shaft. It should not turn. If it doesn't the problem is in the front axle engagement system. The most common faults are: Cracked vacuum lines to the Actuator Motor. Faulty Actuator Motor and faulty solenoids. Do you have a vacuum gauge/pump?

 

i will try asap.... i do not have vacuum gauge....

 

the actuator is right on top of the front axle housing correct? i do seem to remember when i put my oil pan in i had to drop that axle and i remember seeing a black hose not connected to anything.... probably supposed to go that actuator huh

 

No, the black hose is the breather tube. It follows the vacuum lines up into the engine compartment. Keeps water out of the axle.
The solenoids on the firewall have coloured lines leading to the Actuator motor on the axle. The blue line feeds the lockup and the red line feeds the unlock. The vacuum motor has a double dashpot with vacuum on each side. Applying vacuum to the blue line should lock the front axle. You need to remove the cover to see if the lever moves. Applying vacuum to the red line unlocks the axle. If vacuum doesn't hold unplug the lines at the actuator and apply vacuum to the ports one at a time to see if the actuator moves. The outboard port locks and the inner one unlocks. If the motor holds vacuum and the lines did not the lines are leaking. If the motor doesn’t hold vacuum replace it.