All,

2019 F-150 Lariat 4wd.

I have read through the common IWE/solenoid issues on this forum and feel like I have something different. About a year ago I brought my truck in to the dealer for a front end noise when 4x4 engaged that turned out to be a bad wheelbearing/hub assembly. While attempting to diagnose this they referred to a TSB to bypass the 4wd solenoid by capping the vacuum source line and thus keeping the front IWEs engaged at all times. Fast forward a year later and I am getting a lot of drivetrain noise. Nothing specific or obnoxious but it is louder than it was. I decided I would remove the vacuum caps and reconnect the solenoid vacuum to eliminate the frond end as part of the issue. After reconnecting the vacuum line I found that the front IWEs weren't unlocking. I checked power at the solenoid and it was 14v however there was no ground. I jumped this wire to ground and the solenoid applied vacuum correctly and unlocked both hubs.

My question is what system here is not applying the ground switching to activate the solenoid when in 2wd? How do I further diagnosis this? I have verified all 3 4x4 fuses are fine and there are no indicator lights on the dash.

As an aside, the noises I was hearing went away after driving with the hubs (CVs) unlocked. I firmly believe that Ford's TSB has put a lot of unnecessary wear on the front end causing this issue but that is a conversation for another day.

Appreciate any help.

Mike

 

Mike, I am having the same issue you're describing. Vacuum lines are fine, solenoid has been replaced. Check valves are fine, and plenty of vacuum being supplied to the solenoid. No vacuum from the solenoid in any 4x2 or 4x4 switch position. Neither the old or the new solenoid will operate due to something not applying the necessary ground to the solenoid to disengage the IWEs. All of the 4x4 fuses are okay as well. Both axels are spinning all of the time, regardless of 4x4 switch position. The front end on my 2019 is unnecessarily loud now, and I'm sure it's getting worn out quicker than usual.

I don't see any replies to your question/post. Did you ever find your solution..!? Thanks for your time.

 

Im having the same issue with the same type of truck. Mine will also make the noise if I use the key to start it but not if I use the remote start. Did you find out what the issue was with yours?