2000 xlt 5.4 4x4 off road package,
Just got truck 2months ago,now it is snowing,Thought the 4wd was working but what do I now,was out in the snow and put it in 4wd could not tell a difference,was sliding around,checked things out in the garage,Have mechanical experiance,at least some,checked the solinoides wireing on the fire wall,both 2w and 4w have 14 volts across terminals with truck running,Switched to 4wd voltage at both solinoides do not change,can hear a clicking like a relay sound when swiching back and forth from 2w 4wl 4wh,The indicator 4x4 is lit,Looked at the plunger that the vacume lines connect to could not tell any movement ,can move plunger a little by hand.Just lubed plunger armature area tonight to see if that helps,Any experts out there got any ideas of posible priblem?Dont think its the Gem Modual can hear a click and everything else in the truck works fine,But what do i know!

Also can anyone give me a detailed explanation on how the 4x4 system works in this perticular truck?I see there is lots of differant ways they have manufactured 4x4s .... I Have a 2000 XLT Supercab 5.4 style side,shift *** is on dash 2w/4wh/4wl... Thanks for any Help out there!!!!!!!!!!

 

Check the vacuum at the solenoids, not just the voltage. If the diaphragm at the front axle is not moving it's either the diaphragm itself, the lines going to it or the solenoids.

https://www.ford-trucks.com/forums/9...-question.html

https://www.ford-trucks.com/forums/6...nt-engage.html

 

pull both vacuum lines off of the vacuum cylinder on the axle. one side will have vacuumm when in 2 x 4, the other has vacuum when 4 x 4. if you do have vacuum, take the cylinder off and clean.