I have a 2007 Ram, 5.7l, 4x4 and in icy conditions if I brake hard in 4x4 mode my ABS does not work. All the wheels lock and I'm in regular braking mode, no ABS lights are on or any other codes. Has anyone seen this?

 

I am almost certain it's normal. I had an 04 that did the same thing.

 

I believe it has to do with the fact in a part-time 4x4 like the Ram the front and rear differentials are locked together rotationally via the transfer case and the wheels can't turn at different speeds. ABS allows the wheels to each brake at different speeds to prevent lockup, so it wont work well or at all in 4x4 mode since the wheels can't turn at different speeds because of the transfer case.

 

Normal. transfer case and axles. its called 4x4.

all 4 wheels are powered equally. so are the braking.