Two problems related to transfer case have been reported for the 2018 Ford F-150. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2018 Ford F-150 based on all problems reported for the 2018 F-150.
2018 f150 4x4 lariat the issue is 4x4 is engaging while your driving I’m on the highway speed 65 to 70 mph 4x4 trying to engage. Doing research Ford sent united state wide message to mechanic if customers bring vehicle in under this issue which is TSB technical service bulletin 22-2219 , think this is a safety issue if 4x4 engage is going to veer your vehicle in a different direction, the fix is to bypass the check valve so now your vehicle front axle is always engaged,didn’t purchase this vehicle to be all wheel drive.
The vacuum actuator tries to engage the four wheel drive on it's own. It is a common problem on the f150s. My truck tries to randomly engage the four wheel drive system every 50-75 miles, typically at 55-65mph on the highway. When this occurs you can hear the cv axels grinding against the transfer case gear until you slow down or physically engage the 4x4 system. This will eventually wear out the front drivetrain or worse, further engage unexpectedly and potentially leading to loss of control and collision.