Dear Y'all, I have a "plastic dragging on tire tread" sound on my 2018 F-150 Platinum mainly, though not always, at lower speeds. Switching from 2A to 4A and back again will alleviate the sound and leads the dealer (who can't replicate the sound) to believe it is a vacuum issue affecting the driver's-side hub. Dealer states that because they can't replicate the sound, they can't diagnose it, give it a code and get authorization to fix it under the extended warranty. I want to believe that, but have my suspicions. Do any of you have a suggestion for a path to solving this (these) issue(s)? Many thanks in advance.

 

IWE. Vacuum test the lines and actuator individually and see which is at fault

 

Also test the check valve right. You should only be able to blow through it in one direction. If both, definitely bad. If only 1 direction, it could still be bad as they have been known to work intermittently.

 

What happens when you shift to 4A and leave it in that position for a while (e.g., days)? If the sound goes away, it is likely related to the IWE.

 

I recently had the same issue, and dissassembled the entire hub assembly and IWE, cleaned with brake cleaner, re-installed with fresh new grease, and the sound went way.
It's worth a shot if you have exhausted all troubleshooting steps.