04 Exp clunking in AWD or 4WD

[FordFairLane]

So took a trip and the roads were slick so I put it in AWD and every once it awhile it would clunk something awful almost like the dront end was trying to engage into 4wd but could not. I was only going 40 when I put it in AWD and stopped a few times so it should of been able to engage. I put it back in RWD and kept going. Later in the city it was bad roads so I put it in 4WD hi and seemed fine until I got going back over 40 again. Have no clue what it could be.

 

[mindgame]

Highly likely a bad IWE Solenoid.. ~$40 part, 5 minute fix..