2008 f150 20k mileage.

I had a problem with the Iwe's engaging while driving off and on.
I diconnected the main Vacuum line to solenoid and plugged it.
All was good so I could drive without damaging IWE and Hub.

Here is the New or maybe the reason for the problem.
The solenoid will start to make a tapping noise while not in 4wd.
I was stopped at a light and heard a tapping like morse code coming from the right side of the dash. I pooped the hood and the solenoid for the iwe was clicking away. I unplugged it and it stopped.
Also there seems to be a seam in the part and has a grey locking film leaking out of it.

Now the question is How does that solenoid work? Does it have power at all times to keep in 2wd? Or should it only get voltage when in 4wd!

 

At the solenoid:

The pink/light blue wire is voltage at all times.

Red wire is "4x4 center axle disconnect solenoid control"

 

Looks like the PCM grounds the red wire to activate the solenoid.

 

So do you think that the Solenoid has gone bad and keeps opening and closing? I would think that this is why the IWE keep trying to engage.

 

Either that or the wiring got nicked and is grounding out.

 

The red is hot always? So does that mean the pink is the triger to open and close solenoid? I may buy a new solenoid and plug it in to the harness and see if it starts clicking. Thanks for the info. Do you have a wiring Dia, of the harness ?
I may check for voltage change on Pink wire.

 

No, looks like the pink/blue is always hot. The red just grounds to the PCM completing the circuit on demand.

 

The solenoid has a little grey stain on it like it was leaking something.
Is it possible that the plunger inside is not staying energized and is clicking on and off? You can hear it tapping whne in 2wd.

 

Definite possibility.

You could replace it, and just return the new one if it doesn't fix the problem.

 

I ordered one for thursday, It will not go into 4wd with out the solenoid pluged in. I will try a new one and if that is it fine if not I have a spare. LOL I think it may have sucked in some salty street water from all the snow and that is what the gray film is. If not I will take it apart to see what it i inside this solenoid.