4WD Auto

[HMC8403]

Just wondering what setting most use in the summer with dry roads. Does 4WD Auto keep you in 2WD if there is no slipping, is there an indicator that shows what drive is engaged when in the auto setting?

 

[SpeedyV]

Just wondering what setting most use in the summer with dry roads. Does 4WD Auto keep you in 2WD if there is no slipping, is there an indicator that shows what drive is engaged when in the auto setting?

2WD unless it’s rainy. Auto 4WD won’t really harm anything except economy, as you’re spinning extra parts.

I don’t remember it doing anything when it “kicks in”...the green Auto 4WD light just stays lit while you’re in that mode.

 

[Helmetface]

2WD unless it’s rainy. Auto 4WD won’t really harm anything except economy, as you’re spinning extra parts.

I don’t remember it doing anything when it “kicks in”...the green Auto 4WD light just stays lit while you’re in that mode.

Is there a reduction in fuel economy when in Auto4WD, but not slipping/activating the front?

 

[SpeedyV]

Is there a reduction in fuel economy when in Auto4WD, but not slipping/activating the front?

Yep, but it wouldn’t be a lot. Certain components are engaged in order to be “ready” for application of torque, and that creates parasitic drag on the driveline.

 

[Thewrangler73]

So does anybody else use 4wd auto on the highway when it's raining? I use it then, but a lot of people tell me it's useless for that.

 

[riccnick]

So does anybody else use 4wd auto on the highway when it's raining? I use it then, but a lot of people tell me it's useless for that.

They're be incorrect.


Running 4auto at any speed allows the truck to automatically engage 4wd when it detects wheel slip. Can't do that in 2wd...

 

[Helmetface]

They're be incorrect.


Running 4auto at any speed allows the truck to automatically engage 4wd when it detects wheel slip. Can't do that in 2wd...

Maybe their point is how effective 4WD kicking in while doing 65mph+ in the wet would actually be.

 

[saxapl]

The necessity of using 4wd on pavement in rain is questionable. It will not impact braking or hydroplaning performance, only traction under acceleration. An alternative is to reduce acceleration to match the weather conditions, which is easy with rain, but more difficult with snow and ice.

That being said, if you paid for it and feel more comfortable using it, the downside is only the aforementioned fuel economy loss and increased wear on driveline parts in front of the transfer case. Small prices to pay...it is not like you are going to run out of 4wd.

 

[Wolf]

You/they need to think of 4auto as AWD on any other car/vehicle. That is essentially what it is. Noticeably better and advised in snow and rain at any speed, has been my experience. I'm on my 4th Ram with it.

The all terrain tires on the old Outdoorsman, the new North Edition and any Ram with the Off-Road package handle much better in the snow and rain than standard Big Horn tires of any year.

 

[saxapl]

You/they need to think of 4auto as AWD on any other car/vehicle. That is essentially what it is. Noticeably better and advised in snow and rain at any speed, has been my experience. I'm on my 4th Ram with it.

The all terrain tires on the old Outdoorsman, the new North Edition and any Ram with the Off-Road package handle much better in the snow and rain than standard Big Horn tires of any year.

This. Tires are the biggest factor in the traction game. Better to have good tires and 2wd than 4wd and slicks. I have not used the Wildpeaks, but they look significantly better than the street tires on my 22s. Before winter, there will be a second set of rims with snow rated tires.

 

[StuartV]

I can't really agree with those that saying Auto is useless when driving on the highway in the rain.

I ended up in the ditch in an F250 I had one time (my brother was driving) because the cruise control caused the truck to downshift while going up a hill in the rain. The back tires spun and the truck turned sideways. If that truck had had 4WD Auto, I believe the front wheels would have pulled it out of that and kept us on the road.

That's just one example. Here's another.

I was going down I-66 in my '09 1500 (which was 4x4, but did not have Auto). It was winter. I went over a patch of ice. I guess I was slightly accelerating (or giving it gas to maintain speed) just at the moment. The truck started to get sideways then. I managed to steer out of it and keep it on the road. But, again, I believe if I had had Auto (and been using it, of course), the front wheels would have pulled me out of that, instead of getting sideways.

My old 1500 did not have 4WD Auto. My new one does and I am glad for it. I will definitely use it any time there is a chance of hydroplaning or other sliding on wet pavement, or if there are icy/snowy conditions.