Slight drone when I have my Ram in 4WD Auto

[Brisoup1]

When the roads are wet, I usually put my truck in 4WD Auto. When I accelerate, I hear a slight drone coming from the front end of the truck and feel a very slight vibration in my steering wheel. The service 4WD light does not come on. When I put the truck back in 2WD, the droning/vibration stops. I haven't needed to put the truck in 4WD high/low yet, so I don't know how it'll act when I do that. Any Ideals on what can be causing this before I take it to the dealer?

 

[kapinallinen2]

When the roads are wet, I usually put my truck in 4WD Auto. When I accelerate, I hear a slight drone coming from the front end of the truck and feel a very slight vibration in my steering wheel. The service 4WD light does not come on. When I put the truck back in 2WD, the droning/vibration stops. I haven't needed to put the truck in 4WD high/low yet, so I don't know how it'll act when I do that. Any Ideals on what can be causing this before I take it to the dealer?

Sounds normal, you are turning the front axles and differential/ front drive shaft.

 

[Brisoup1]

Sounds normal, you are turning the front axles and differential/ front drive shaft.

But when I'm in 4WD auto, the front drive shafts is only supposed to engage when slippage is detected. This droning/vibration is constant, no matter how fast I'm going or If I'm driving stright or turning.

 

[Gdwheel]

Mine does it too.

 

[202snowman]

I hear the same thing with mine...never been concerned with it

 

[kapinallinen2]

But when I'm in 4WD auto, the front drive shafts is only supposed to engage when slippage is detected. This droning/vibration is constant, no matter how fast I'm going or If I'm driving stright or turning.

In 4 auto the front drive-line is turning and when wheel spin is detected it is coupled to the transmission by a clutch pack in the transfer case, providing torque to the front wheels. My Expedition functioned like this also and I could tell from the low rumble that all was good and working as designed.

 

[magic280z]

But when I'm in 4WD auto, the front drive shafts is only supposed to engage when slippage is detected. This droning/vibration is constant, no matter how fast I'm going or If I'm driving stright or turning.

When in 2wd the front diff ring gear separates from the pinion putting the front end in neutral. When in any 4wd mode including auto the ring gear slides over to the pinion engaging the front driveshaft. The auto part is transfer case engaging drive power to the front driveshaft.

You can verify this by spinning the front driveshaft by hand in 2wd.

I too have the vibration in 4auto. Truck based 4auto isn't as refined as modern car based AWD systems. It is basically an electronic operated clutch engaged 4hi since the center transfer case is locked instead of behaving like a diff or limited slip.

2019 Ram 1500 Laramie - Crew Cab/5.7 Bed - 5.7 Hemi - 3.92 - Anti Spin - Level 1 Options - RamBox - BUG

 

[kapinallinen2]

From the owners manual.
For variable driving conditions, the 4WD AUTO mode can be used. In this mode, the front axle is engaged, but the vehicle's power is sent to the rear wheels. Four-wheel drive will be automatically engaged when the vehicle senses a loss of traction. Because the front axle is engaged, this mode will result in lower fuel economy than the 2WD mode.

 

[Brisoup1]

Thanks for the Input! As long as the Service 4WD light stays off it'll be a non-issue then....

 

[kapinallinen2]

Thanks for the Input! As long as the Service 4WD light stays off it'll be a non-issue then....

Yes.

 

[My1stHemi]

Wow, I started using 4wd auto and 4wd high over the last month and this growling noise did not give me a warm and fuzzy feeling. My wife’s Grand Cherokee has a silky smooth AWD system and my last truck had a Cummins, so I never heard driveline noises I am glad to hear that these sounds are normal.