Hmmm, sounds not cool. I'd check the vacuum hoses as a guess. I've never had the problem, but i think some people on this board have had problems with the hoses loosing pressure and not locking the front hubs? Maybe i'm completely off, but its a guess...sorry i can't help ya more.
-Brandon
97 F150 Xcab Glossy Bright Red 4x4
4.6L v8
3.55 LS
285/75R16 (soon 315/75R16 Geolander MTs)
stock rims (soon 16x10 A.R. Atlas)
Clear Corner Lenses
Westin Nerf Bars
Performace Acc. 3" body lift
Blue Neons
Stereo:
--Pioneer 8000 Series 3D Face
--(4) 5x7s Boston Acoustics
--Sony Xplode Amp
--(2)Rockford Fosgate 8" subs

 

I have a 99 F-150 4X4 4.6 and I can not get the 4X4 to work in High or Low. When I turn the **** to 4X High it makes a slight sound like it is engaging but the front wheels never pull. I tried 4X Low and had the same result. I noticed this in the snow going up a driveway when my rear tires started spinning I stoped put it in 4 Wheel High and just kept spinning the front tires did not move at all. I put it in neutral and then put it in 4 Wheel Low and got the same result the front wheels will not pull at all.
I check the fuse box and the fuse seems fine I don't really know where to go from here has anyone expieranced the same problem if so where do I go from here????? Any info would be more than appreciated.

Thank You,
Kevin

 

If you can, put the truck up on jackstands and start it, engage 4WD. When 4WD is engaged the pink vacuum line (disengage) on the driver's side of the diaphragm should not be pulling ANY vacuum. If you remove the pink line and the actuator rod recesses further then the disengage solenoid is bad. If the rod doesn't recess at all then the engage solenoid is bad or there may be a vacuum leak on the blue line. Worse case: switch in transfer case that energizes the solenoids is bad (check wire connection with voltmeter @ solenoid in 4WD and 2WD). Worst case: something's broken in the diff. Solenoids: On the firewall behind the battery, passenger side is engage, driver side is disengage.
NOTE: applies to 97+ only

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1997 F150 4.6L 5speed SC 4x4