4WD Engaging/Disengaging (IWE operation) in 2019 Expy/F-150/Navigator

[BinaryExpert]

I have a 2019 Max and hear subtle metallic noise and vibration randomly from near my front wheel (They are usually pronounced within first 5 minutes of driving in the morning). From my service visit, I have learned new information to share with you.

SSM 48088 - 2019 F-150/Expedition/Navigator - 4WD - Revised IWE Operation Strategy After Initial Start Up
2019 F-150/Expedition/Navigator vehicles equipped with four-wheel drive (4WD) have a revised transfer case control module (TCCM) strategy that will affect IWE operation after initial start up. The TCCM will not energize the solenoid to supply vacuum to the IWEs after the initial key cycle and a driven gear is selected. The IWEs will remain engaged for 0.8 km (0.5 mi) when the temperature is above 0 C (32 F) and 3 km (2 mi) when below 0 C (32 F). The strategy changes were implemented to improve vacuum supply management and axle warm up in cold temperatures. The engine must run for a minimum of 5 minutes to build sufficient vacuum before performing any vacuum related testing. Refer to the workshop manual section 307-08A.

 

[powerboatr]

makes sense for cold weather ops.

wonder if it will migrate down to prior years?

 

[ETC13]

Looks like my 2018 needs to go in for this. At first I thought it was the hub bearing, but after looking up some videos for F-150's on how-to replace the hub assembly came across one that was replacing the actuator. Sound lined up with what he showed in the video of the actuator not fully disengaging. On next drive shifted it to 4A and sound went away...

Seems to be a common problem on the f-150s since there is an aftermarket vacuum actuator delete which would place it into engaged all the time.

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[ETC13]

makes sense for cold weather ops.

wonder if it will migrate down to prior years?

2018 was already listed with a TSB.

https://ford.oemdtc.com/4748/interm...-2018-ford-expedition-f-150-lincoln-navigator

Top of the TSB only mentions F-150, but when you get to the actual service procedure clearly is for the Expedition too.

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