Good ol' F150Forum, your collective knowledge certainly came in handy
Driving down the road, I hear this loud grinding that appears to be emanating from the driver side hub. Thankfully I'm running around the city and not the interstate so I quickly dash into a parking lot and get 'er stopped. Upon deceleration, the grinding sound came to a halt by way of a jarring thud. Now, had I not invested countless hours on this site, killing time, I might have begun to panic. Lucky for me, I've read up on all the issues my 06 is prone to.
I hop out of the truck, do a quick run around. I didnít see anything hanging off. I look under the truck, don't appear to have run over anything... Thinking back to my many hours of reading on here, I'm drawn to the poorly engineered 4wd solenoid. Sure enough, it's the "old" style.
So, I picked one up at my local stealership ($28) and head home, in the rain, to start My Saturday Project.
The solenoid in question is located on the passenger side of the truck. It's right behind the battery. I was able to do this project without completely removing the battery, but you may find it easier to work if the battery is taken out completely.
Here is a picture of the "old" style solenoid. As you can see due to a lapse in engineering judgment, they place the unit in such a manner that it is constantly subjected to water and drainage. This causes the unit to engage at random times. If interested, there are many many threads on this forum which give a much more in-depth and technical description of the problem.
I start out by disconnecting the connection to the negative terminal on the battery (8mm socket). After this is done, I use a flat blade screwdriver to gently pry off the plastic strap/wire holder (located on the right stud in the picture). Once the strap has been removed, I use a 10mm socket to take off the two nuts that hold the unit in place.
Once the unit is off, I push down on the clip on wire harness connector and pull back to remove it from the old solenoid. This could be done prior to removing the solenoid and would probably make removal much simpler. After the wiring harness was disconnected, I firmly grasped the vacuum line connector and gently wiggled it back and forth until it pulled loose. A hissing sound can be heard as the lines decompress.
I then pushed the vacuum line connector onto the new unit and placed the it over the studs that held the old unit. I replaced the two nuts and pushed the plastic strap back in place. I then plugged the wiring harness back into the new unit. I replaced any lines/wires I may have moved around during the install. After all of this was done, I reconnected the battery and started the truck to try it out.
The whole project took maybe 10 minutes. Very easy (and cheap) project. If your truck is out of warranty and you have the old style solenoid, this is a project you're going to want to do!
Here is a closeup of the new solenoid: