On my 2019 Lariat, humming noise from front end was coming from the front diff bearing being shot. Dealer replaced front wheel bearings. Still noise. They pin point the feont diff being the cause by driving the truck with front drive shaft removed. No more noise. Internal bearings where shot. In a Lariat with 4a transfer case, front diff spins all the time in 2wd. If yours is an XLT, the front diff should not spin in 2wd.

 

In a Lariat with 4a transfer case, front diff spins all the time in 2wd. If yours is an XLT, the front diff should not spin in 2wd.

Just asking, but why would the front differential be spinning if the truck is not set to 4A?
Or put another way, if set to 2H, the transfer case would have no need to spin the front differential since there is no circumstance that the transfer case would "transfer" torque to it. And wouldn't the IWE's be disengaged in 2H anyway, thus even less reason to spin that front differential?

These days, the manufacturers go through a lot of effort to save drivetrain fuel economy. Seems strange that they would spin that front differential (energy loss) if it serves no purpose.

Just curious. I love the 4A feature, by the way. Use it quite a bit. But I guess I still don't understand it completely.



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OP, does the grinding noise go away in 4A?

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