I have 08 F150 that the 4x4 is not working on.The light on the dash comes on and I can hear the transfer case engaging.I checked to make sure that I have vacuum to the switch under the hood and that the vacuum line going down to the front diff is holding vacuum.I'm just not sure how it engages the diff.Can someone help.

 

Vacuum does not go to the front diff. It goes the the Integrated Wheel Ends located at both knuckles. You either have a failing 4x4 solenoid located on the firewall behind the battery and it is stuck in the open position supplying vacuum to the IWE's. OR have an IWE that is stuck in the unlock position. Disconnect the vacuum hose at the knuckle and see if the axle locks to the wheel bearing/hub. IF so, you probably have a failed 4x4 solenoid.

 

Ok Itried that and on the drivers side the axle locks to the hub,but the passenger side doesn't. I pulled the vacuum hose off at the hub and there is no vacuum when the switch is on 4x4.There is vacuum when switched to 2x.So I think the solenoid is working.Is there a way to check if the IWE is stuck or defective.

 

Jack the wheel up and disconnect the hose to the IWE. Spin the wheel. If the wheel spins without the axle with the vacuum line disconnected, the IWE is bad. Vacuum unlocks the hub, and no vacuum locks it. IF you are unlocked w/ the lines disconnected then the IWE is bad.

 

Ok,I tried that, the IWE must be bad.Is it a big job to change?

 

Not to bad. Maybe an hour a side. Disconnect the upper ball joint from knuckle. removed the axle from the knuckle, then loosen and remove the iwe. check the wheel bearing gear for damage. If the iwe was bad long enough, it rounds off the edge of the gear, meaning you will need to replace the wheel bearing too.

 

I might try to do it myself.I'll order the parts tomorrow and see how it goes.Thanks for the info,I'll let you know how I make out.

 

Thanks for the help.I ordered the parts and got them a while ago,but I was waiting for the weather to warm up to install them,cause I don't have a heated garage.Well the weather wasn't warming up so I braved the cold -15C or 5F and changed it.The job went well and it worked.It was alot simpler than I thought it would be.Thanks again.