Hey everyone. I have an 06 f150 xlt 4wd 5.4. I bought the truck about two months ago and have come to realize that my 4wd is not working. The light works and you can hear the clunk but recently we got alot of rain and i was going down a georgia clay dirt road and almost got stuck in the middle of the road. i tried 4hi and 4lo but only the rear wheels would spin. I know there is alot of threads on this already but i cannot figure it out. I also read the "Everything you need to know about the IWE" thread. I had my wife put it in 4wd while i looked under the truck and the half shafts do turn in 4wd. which doesn't make any sense to me. i also unplugged to vacuum line from the intake and capped it off to try and let the hubs engage that way but still nothing. why would the half shafts be turning but no power to the front wheels in 4wd? does that mean the iwe's are stuck engaged? Which would explain why they turn all the time. But if they are engaged, whether they are stuck or vacuum leak or whatever the reason, shouldn't the front wheels be getting power. What else should i be looking for? Sorry for the long post hopefully i gave you guys enough info. Thanks in advance.

 

on the newer trucks ( after 2004) you have the "IWE" ... im no expert, but I believe the axle half shafts will turn and the "ENGAGEMENT" is at the wheel hub end. Read the IWE again. You have a vacuum loss at the outboard end by the hub. (vacuum controlled) . I would look toward the solenoids.

 

-If when you try to shift into 4WD and it will not engage, most likely your solenoid is not working and releasing the vacuum to the actuators and engaging the hubs. Replace the solenoid. This might happen because of the early design of the IWE solenoid with lets water run off the cowl right down on top of the solenoid possible shorting it out. The new style solenoids have a rain cover on them to prevent this. This is all being said as long as you know your shift motor on the side of the tranfer case is working properly.

 

i removed the lines at the iwe's and switched from 2wd to 4wd and the vaccum did stop at the supply line at the iwe. Does that mean the solenoid is working correctly? When i switched it back to 2wd it got vacuum again.

 

so your saying the actuator is stuck and not moving ? if you have vacuum, and it turns on and off, then either you have 4 x 4 or the actuator is not engaging .. right ?

 

I would also check for proper vacuum pressure, not just "present"... the IWE writeup has some good steps...

One wheel at a time unplug the double vacuum hoses from the actuators at the wheel located behind the steering knuckle. Put your vacuum pump on the big hose fitting and pump up the pump. If it is woking correctly you will be able to build up vacuum and it will hold. A vacuum loss of 1 lb over 1 minute is acceptable. If you can not build vacuum or is leaks down very fast, the seals on the actuator are shot and the actuator needs to be replaced.

Next check your lines from the solenoid to the actuators at the wheel. Pull the double vacuum line off the solenoid. Pull the double vacuum line off of both actuators at the wheels. Plug the hoses at the wheels. (you only need to plug the big hose a the wheel, and make sure you have a good plug that seals 100%) At the double hose that you took off the solenoid, trace the lines, you want the line that goes down to the wheels, not the one that goes to the intake. Take your pump and connect it to the line end from the solenoid that goes to the wheels. Pump the pump up and see if the vacuum on the guage holds. If it does not and leaks down, you have a leak in your lines between the solenoid and the actuators. Check the lines very thoroghly from the solenoid to the wheels, its hard to get to some of the lines, but they all need checked, look for cracks or breaks. Replace the lines with factory ones from ford or make your own, like i did with bulk vacuum hose and some fittings. If the vacuum you create with the pump holds your lines are good, but still look them over for obvious faults.

 

When i switched it back to 2wd it got vacuum again.

You realize the "NORMAL" position of the actuator is 4 x 4 engaged... When you start the motor and get vacuum, you can "disengage" and go to 2 x 4... your right, the vacuum pulls the actuator back to 2 x 4... without vacuum , the actuator should be engaged and in 4 x 4

 

I do understand that without vacuum 4wd should be engaged. That is why i believe the solenoid is working properly. What i don't understand is with the main supply line coming from the intake plugged why i still don't have 4wd unless the iwe's are shot. When I unplugged the line coming from the intake i drove it a little ways. When I put it in reverse i heard the classic rattling sound from the front driver hub when in 2wd. I'm going to find a vacuum guage tomorrow and test everything the right way.

 

sure sounds like it is in the IWE, since you have the vacuum OFF... Most people have problems with not enough vacuum and leave the 4 x 4 partly engaged and "rattling"... seems like something is "STUCK" inside your wheel end.