First of all, 2004 newer style F150 with a 4.6, and stick shift 4wd.

The 4wd just doesn't seem to be engauging? Pull the shifter, and it just doesn't work. No bangs, clunks, anything. Just no 4wd.

I'm not super knowledgeable about the 4wd system, but heres what i've done so far.

I've checked all the inside cab fuses relating to the 4wd system according to the owners manual. All appear fine.

I got under the truck, with the shifter in the 2wd position, and I can grab the front drive shaft and turn it. I then shift to the 4hi position, and then I can't spin the shaft. I don't know if thats any help to anyone, but thats all I have right now.

Anyone have any ideas, or tips to try before I have to result to talking it to a mech? I prefer to do stuff myself, so if anyone has any pointers, please guide me. Thanks!

Ryan

 

Have you tried giving it a kick I do know on mine which is on the fly, that when it doesn't engage i use to kick the side of the wheel and jiggle the hydraulic line, it seemed to work sometimes

 

Four-Wheel Drive Systems Printable View (13 KB)
Mechanical Shift

The Borg-Warner 44-06 manual shift transfer case is a three-piece aluminium design. The unit transfers engine power from the transmission to the front and rear axles. Under normal driving conditions the unit is in 2-wheel drive high (2H), but when desired, the operator may shift into 4-wheel drive high (4H) or 4-wheel drive low (4L). The transfer case is shifted manually. The unit is lubricated by a positive displacement fluid pump that channels fluid flow through holes in the rear output shaft.

Principles of Operation

The mechanical shift on the fly (MSOF) system is a manual shift 4WD system that allows the operator to chose between two different 4x4 modes as well as 2-wheel drive and neutral. The operator can switch between 2WD and 4H mode at speeds up to 88 km/h (55 mph). To engage or disengage 4L range, the vehicle speed must be less than 5 km/h (3 mph), the brake pedal pressed, and the transmission must be in NEUTRAL (or the clutch pedal pressed in manual transmission vehicles).

The transfer case is equipped with an electromagnetic clutch which is located inside the case. This clutch is used to synchronize the front driveline. When the manual shift lever is moved, this activates the mode indicator switch, triggering the 4x4 module (PCM) to energize the electromagnetic clutch. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle integrated wheel ends (IWEs) are engaged and the electromagnetic clutch is deactivated.

Feature Inputs:
Mode indicator switch.
Wheel speeds (via CAN communication).
Feature Outputs:
Transfer case synchronization clutch.
Integrated wheel end (IWE) vacuum solenoid.
4WD mode (via CAN input to PCM).
Cluster Indicators (via CAN communication).

If you can spin the front drive shaft while in 4x4, your'e not in 4x4. Could be the IWE vacuum solenoid or a bad vacuum line leaking

Edit- Not sure where the IWE solenoid is located on yours, but mine is right behind the battery, so if you had your battery changed recently, I would check to to see if any wires, connector or vac lines are screwed up. In any case, hope you get it figured out before winter. I can't do without 4x4 here in winter.

 

see bolded above

 

a picture is worth a 1,000 words as they say. here is part of the diagnostic chart for 4x4 not shifting.





I suggest you try the manual shifting of the linkage

 

GOOD GOD

 

I believe your Transfer case is working fine but you are not engaging the hubs. Put it in 4wd high like you did to test and then drive off. See if its in 4wd. If it wont switch while moving, there my be a problem with the clutch mentioned in the other post.
There is a vacuum solenoid on the firewall to the rear of the battery. I believe that no power to it would engage 4wd (if you unplug it, your in 4wd at the hubs). The switch on the transfer case may not be telling the system to engage the hubs.