<HR style="BACKGROUND-COLOR: #d1d1e1; COLOR: #d1d1e1" SIZE=1 itxtNodeId="682"><!-- / icon and title --><!-- message -->My '05 F150 (92,000 mi) 4 wheel seems like it is engaging and disengaging when activated. Makes a clunking sound on light acceleration then quits when I back off the gas. Not sure if it is engaged then or not. I noticed this on a gravel road when I had turned 4x4 on to distribute oil around the system since I had not used it in a while.

Any ideas what it might be and if it is any easy fix or a trip to the shop.

Thanks for your help.

 

Mine makes a noise also and has done it since 30k miles when I bought it (96k on it now). I don't know what it is but the 4x4 seems to work and I assumed mine was a common noise in 4 high. Never does it in 4 low and won't do it unless I'm slow speed, most frequently when I'm turning. I also have a 6" suspension lift, don't know it that has anything to do with it.

 

I just went to check mine again and it is not engaging. I think the clumking noise is the transfer case trying to go into to 4 wheel but doesn't. Maybe the solenoid?

 

1. Use this to troubleshoot the solenoid and/or vacuum system;

https://www.ford-trucks.com/forums/836438-everything-you-wanted-to-know-about-the-iwe-system-and-then-some.html

2. It is also possible the shift motor (on the transmission housing) is sticking or has a short. You can try tapping on that with something like a wooden handle to see if it will loosen. (like when a starter solenoid is sticking)

3. There are a couple electrical relays on the firewall in front of the driver side that could be at fault, but I'm not that familiar with them.