Just want to thank the contributors to this thread, especially xjcamaro89, for a great, informative series of posts. I have a manual but this gives it a better perspective with some real world situations not covered in "the book." This oughta be a sticky but I have printed it out and filed it away in case I have trouble.... plus I put a vacuum line inspection on my PM list. Good work!

Your welcome. This thread is actually in the tips and tricks sticky at the top of the main 04-08 page. I really think this article has help a tremendous amount of people, not only here, but on other boards as well.

Great info - I wish I would have seen this over the summer. We were on vaction when we heard this awful sound while we were going down the freeway. Not the type of sound you want to hear on a brand new truck you that you only had for 6 months (2008 F150). The dealership said that the vacuum line had come off the right front and they has seen this problem before. The electric lock up on the fan also went out on this trip causing the engine to get hot. I guess I made somebody mad. I will have to read this post again to prevent future problems.

Hey guys, Just want to remind you all that if your still getting the grinding, and can find NO other reason, go to O'Reilly's and get 2 of the HELP! brand vacuum check valves and replace the two in the system, one between the intake and the solenoid, and one in the tee before the solenoid

I had this problem, could figure it out for the life of me, until i tested the check valves by mouth. Ya, suck in and blow out on them. if they let air both ways, even a little, replace them. The whole assembly from ford is expensive, the parts are like 5 bucks.

My '04 is gone, traded, but I'll never forget getting that figured out.

Just wanted to verify what I read... My truck will switch from 2wd to 4H and into 4L just fine but when I try to go back to 4H from 4L or back to 2wd it sometimes takes minutes. I usually end up having to mess around with the throttle and 4x4 knob and pray. Does this sound like the solenoid?

No, sounds like you need to be in Neutral (instead of park) when you shift out of 4L. (binding a little maybe in park.) 4L is not a shift on the fly setting. only between 4H and 2wd can you shift moving. 4L, as I've always done it, is stopped. Older Mechanical shift said you can be going up to 5mph. Never tried it.

OK, I'm brand new here and just bought a 2006 4x4 with manual 4wd shift. I drove it for the first long drive last week (about 400 miles), and twice at highway speeds (50-65) I heard a light grinding sound from the front left. The first time I pulled over and the sound just went away when I stopped. The second time as I slowed to a stop I heard a light "clunk" and the noise went away. Does this sound like an IWE problem? The 4wd system worked fine the couple times I used it prior to the loger drive.
I sure miss my '92 4x4 with the simple manual hubs...

Yes. Sounds like the left IWE actuator is bad. The clunk you hear is the vacuum reaching a level when your slowing down that allows the IWE to completely unengage. When driving the vacuum drops at different RPMs and is allowing the IWE to try to engage.

Well, I already picked up the Haynes book today, so it looks like I'll be getting to know this new sytem. Thanks a lot for all the info you have provided relating to this stuff. G

...well now I'm even MORE grateful for your detailed instructions, as the Haynes manual says not a GD thing about the IWE system, even though it says it covers 4wd. What a piece of published crap! The manuals I've bought before actually covered most stuff for the vehicles. Again, thanks for your information.

I have a 2004 F150 that won't go into 4wd,when I put it in 4wd I hear a grinding noise coming from the drivers side. One person said it was the actuator and someone else says it's the solenoid. but after reading this post I am thinking it may be the solenoid and not the actuator, also everyone says that if it were the actuator it would make noise when it is in 2 wd, what does everyone here think. going to call the dealer tomorrow. But I am also starting to think the guys here know more then the dealer. Thanks in advance for the help.

I would try the solenoid. And i was thinking the same thing as those other people you reference. That if it was the actuators then it would grind while in 2WD, and more than likely you would hear it from one side or the other (or in rare occassions both) but if when you switch into 4WD and then you hear the grind, i would try the solenoid. It might not be letting off enough vacuum to allow it to completely engage. The solenoid is less than $50 (most dealerships) and they will probably have them in stock. Good luck, let us know how it goes!

No four wheel drive
 

I've read through these posts and they were very helpfull. My truck wont go into 4h or 4l I have never heard any of the noises,when i turn the switch nothing happens,no light or engageing of the front end.when i start the truck 4l and 4h both light up but i cant get it to even act like it wants to go in. Please help would you start with fuses or could this still be a vacuum problem. What triggers the idiot lights on the dash is it when the motor switches??my truck is an 06 f150 with the iwe system

If this is the case, and your not getting any lights on the dash and it is not engageing. You are probably looking at the shift motor on the transfer case that actually switches the transfer case into 4wd. i believe something there turns on the idiot lights. If it is not that, then you might be looking at a bad 4WD switch on the dash. A quick way you can see if it is the shift motor on the transfer case is to slide underneath and give the shift motor a couple wacks with a hammer (shift motor from what ive heard looks like a windsheild wiper motor) and then try it. If it then works, you know that the shift motor is hanging up. If it still doesnt work, it could still be the shift motor, but im not sure how to test it. I guess you could get a new one and put it on and try it, if it works your done, if it still doesnt work than put the old one back on, return the new one and start looking at the 4WD switch.

This should give you somewhere to start.

xjcamaro, do you think you could post a pic of the line coming off the intake? Also could you post a pic of the IWE actuator, and the line hooked up in the wheel? I think my 06 has this problem.

Heres a vid of my truck whinnin.

MOV01703.MPG videos from friends & fun videos on webshots

I also, frequently go muddin so their could be dirt in the lines. Also, my truck has a miss when you floor it on the hw but it threw a code and then the check eng light turned of thirty sec later.