It happened to my 04, and the vacuum lines were connected, and I never know when it'll do it.

 

SDTruckMan,
If the lines were completely disconnected, the IWE's would have been engaged all the time. Yours obviously were not engaged all the time, so I don't completely buy their diagnosis of being disconnected. Poorly connected, maybe. Your symptoms are consistent with a smaller leak, grinding when the manifold vacuum is low and can't overcome the leak to keep the IWE disengaged.

Had I seen your earlier post soon enough, I would have suggested just disconnecting and plugging the lines and ports at the IWE's for the drive to the dealer to keep them locked in the whole way without running in 4wd on dry pavement.

With the truck running, you can crawl under the front, disconnect a line, listen to the IWE click in, and verify that the half shaft is locked. If the shaft has to turn more than a tooth to lock in, the teeth on that IWE may be gnarled up. If they just click in every time, you're probably good to go.

The vacuum hose routing near the IWE can be fairly poor from the factory. My friend's truck has almost no slack in the lines between the lower zip tie and the axle so the line gets yanked when the wheel turns. I can see that being a source for leaking eventually.

 

I alternated between 2wd and 4wd on the way over cause I didnt know which would be worse, Roads were wet, is that still considered dry pavement?
Dude.. im not mechanically inclined.. you got any pictures of where the lines are and where im suppose to disconnect at?

 

Wet is better than bone dry for sure.

Just poke your head under there, I think you'll have a hard time missing the vacuum line plugged into the top of the knuckle. It's a siamese'd twin line that is clipped in beside the brake line down to the IWE housing.

 

Well round two for me, started again last night (saturday)on the way to work.
Just had it fixed on wednesday so it lasted 3 whopping big days. I havent been able to climb under the truck to take a look VFR Man cause its been snowing/blowing big time.
Is it safe to drive with the 4wheel drive on?

Im beginning to think that this truck is gonna be a pain in the ****, its been in the shop more times in the past 9 months since ive owned it then my last truck that I own and still have in the last 9 yrs that I owned that.

 

Not on any roads that have substantial traction.

I'd just about bet you have a leak in the vacuum lines or the IWE's are leaking themselves. It usually happens when you're on the throttle and the manifold vacuum is low, right? That situation is a PITA to diagnose since it works fine when the truck is just sitting at idle.

I'd still suggest just unplugging the vacuum from the IWE's until it gets figured out. It's better to drive around with just the IWE's engaged instead of the whole 4wd system. Unplugging the vacuum source line at the solenoid and capping it off is probably the easiest way now that I think about it again.

 

On throttle yes, if im off throttle but still moving you cant hear it other than a hum type noise. Not sure what you mean by "manifold vacuum is low". How do you know?
I took a quick peak under the truck last night. Is the connection your talking about on the front side of the wheel or back side of the wheel?
Know you said eariler that it was 2 cables that Y off from each other. Which I saw but not sure which one is which

 

When the throttle is closed, the intake manifold vacuum will be the highest. When it's wide open, intake manifold vacuum will be the the lowest.

The connection is pretty much right on top of the steering knuckle, just outboard of the outer CV joint of the half shaft. The vacuum line is siamese'd, a big one molded next to a smaller one, two in one. It doesn't split, it plugs on to a double barb.

See that lowest zip tie spot in the background? That is a prime suspect for leaks in my opinion.

Damn, I need to get that friggen salt off of there.

 

Well got to the dealer, they took me right in. They put it on the rack and I got to see under the truck with the mechanic. He told last time the drivers side was unplugged. Told him that it sounded like it was coming from the passenger side. So he checked and that side was plugged in so we went to the drivers side and that side was unplugged. He thought it was odd that it had come unplugged again.
So we got to comparing drivers side vs passenger side and saw that the passenger side had extra slack in the line. Where the drivers side had the slack but was up farther into the truck. So he pulled it down and attached a ....zip tie.....to hold it down.
He figured that when I turned a tight turn to the right that it would come unplugged due to the cable not having the extra slack down at the axle.
Glad we got that figured out. So how concerned should I be about the zip tie though

Thanks for all your help VFR_Man.

 

Got mine back from the dealer yesterday and no problems yet. They changed the solenoid.
SD while it was on the rack did they turn the wheels to see if it would go full travel in both directions? If it doesn't I'd replace it with a longer piece of hose. Guess you could splice some and zip tie and seal the ends to keep water out.

 

Better yet we took it for a drive and took some tight turns.

 

Judging from my '07 and my friend's '05, yours should have had the low zip tie like shown in my picture. The line is just clipped beside the brake line most of the way down, but the last, low point is a special zip tie which clips on to the steel brake line and has a little fin in it that actually bites into the vacuum line a little when the tie is tightened to keep the line from pulling through the tie.

I guess it doesn't shock me that yours is missing. My truck was delivered with the line completely unclipped (still zip tie'd at the bottom though) on the passenger side so the line rubbed on the tire until it rubbed a hole through it and thus started my education on the IWE system.

Glad to hear you got yours figured out.

 

Well since I have got mine out of the shop a week ago...I haven't had any problems....I noticed they did install the new soleniod with the shield on it to prevent water from getting on it from the fender wheel.....not sure if they check the vacuum lines for moisture...but I'm sure there had to be some in the lines.....hopefully this was the fix for my truck....but I guess only time will tell.

 

Where is this "solenoid with shield" located, that everyone is referring to.
Got Pics?
Thought Id look to see if my has a shield.

 

Well don't have pics....but I could possibly take a pic this evening and post it later this afternoon....but with the hood up of course....standing on the passenger side where the hinge on the hood is at.....next to the firewall is a solenoid with 2 hoses going to it....its in the corner on the passenger side against the firewall....before mine was just a solenoid...now its a solenoid with a shield around it.....may be different on another vehicle but thats where its at on a 06'.