2500 Cummins 4x4 not engaging

[Tony_2500]

Today extremely cold sun zero and 4 low worked fine in deep snow. Wouldn’t disengage in neutral - drive for about a mile on ice and then when I got to the bottom of a hill out it in neutral and it finally disengaged at 2mph. Later went through a car wash to get salt off the underbody. Got home and snow was deep again put it in 4 high and the front wheels will not spin. Anyone else have this issue? Also when I was in 4 low it was a little stuck and the service abs and brake light were on. After a while they cleared.

There is a lot of ice and snow packed under the body and inside the wheels. Currently have it sitting in the heated garage to melt it off.

 

[Travelin Ram]

Lever, or electric shift? If it is a lever, was it sticking?

 

[Tony_2500]

Electric shift

 

[2020PW]

With out the engine started engage 4wd. Do you hear the front axle actuator engaging? Sounds like an electric motor. Does the 4wd light stay flashing?

 

[Tony_2500]

Yes I can hear it . The light only blinks as it is shifting then it goes solid. On the head unit I have the app “off road pages” it shows the transfer case being locked.

 

[Tony_2500]

It’s been in the garage since yesterday and all the ice and snow have melted off. I plan on testing it soon to see if that changed anything.

I also tried yesterday putting it in the flat tow neutral to disengage both front and back axels then moved it back into 4 low and that didn’t change or make a difference.

 

[Travelin Ram]

If it was a lever, I’d think ice on the linkage, but I assume the electric shift has no external moving parts. I’m going to examine mine later today and verify that.

Have you used the 4x4 and low range on a regular basis, or has it been in 2H since last winter?

It’s very strange that the light comes on solid to confirm the shift. What I would do, assuming the problem can be replicated, is jack up one front tire. Then you can quickly test both failure points.

1- is the front axle disconnect engagingly the RF wheel to the differential and front driveshaft?

2- is the front DS engaged to the transfer case?

As an aside, you won’t always get a successful shift stationary ( e.g. parked). If the TC gears are not aligned properly to move from H to L then they need to spin a bit to mesh. The technique I use is shifting in motion at a very slow speed 1-2 mph.

 

[Tony_2500]

I use 4 high often and was using it since November. I’ve only had to use low a handful of times. I always am moving for the most part when I shift it to 4hi. I’ve only shifted it stationary at a stop light because of ice and the rear end never has great traction.

I will Jack it up and check it out.

 

[2020PW]

A micro switch activates the light for 4wd to illuminate. Disconnect is on the passenger front wheel.

 

[Tony_2500]

It negative 19 out right now so a little too cold to mess with it even in a heated garage. I had to run into town so I’ll let it sit in the garage and warm up a little. Makes me wonder if something is striped out. Yesterday when I was stuck my son said he could see it spinning but the front wheels weren’t.

 

[Tony_2500]

Awe screw it. Time to throw on the carhart bibs and check it out.

 

[Tony_2500]

If I Jack one side up should it be in neutral to test?

 

[Tony_2500]

Jacked up passenger side had it in 4 low and in neutral and it spins freely.

 

[2020PW]

with both tires on the ground and in 2wd I can spin the front drive shaft. With it in 4wd I can not. Try to turn DS in 4wd

 

[Tony_2500]

I’ll give it a shot. Could the actuator be bad and it just sounds like it is engaging I wonder.

 

[Travelin Ram]

Jacked up passenger side had it in 4 low and in neutral and it spins freely.

It doesn’t matter P or N because 3 other tires are on the ground. The transmission output can’t turn, unless the TC is in N.

Do this again and see if the front driveshaft turns with the RF wheel or not.

1- wheel turns but not DS = FAD is not engaging.
2- wheel and front DS turn = TC is in N, not in 4L.

 

[Tony_2500]

Did it again and no DS is not spinning. This truck has only 7900 miles on it lol

 

[Travelin Ram]

If it were mine I’d rather fix a FAD than the TC, so at least there’s that.

FWIW, I would take to to a dealer or someone with a high level scan tool and the knowledge to use that tool. Just to ascertain whether it’s an electrical fault, bad control module, the actuator, or hard parts inside. Firing the parts cannon get expensive fast, and any of the above are suspects.

Wouldn’t hurt to unplug the FAD wiring, clean the connector, and reconnect. And say a prayer it’s just a dirty connection.

 

[Tony_2500]

I would think this would be covered under warranty.

 

[Travelin Ram]

Oh yeah, if you have warranty use it. I just assumed being a 2018 that was over.