How does ABS behave when in 4x4?

[geoffff]

I recently took my van out into the woods, and it barely made it up a steep quarter mile access road covered with fresh 6-inch wet snow, just below freezing. (Next time I'll bring chains!!)

But (even scarier) it barely made it down the hill again later without sliding off the edge into the trees!

I would move downhill a few feet at a time, brakes engaged, as slow as possible, and the rear would always start swinging out sideways. Luckily the van would come to a halt within a second or two when I mashed the brakes. I would then let off the brakes, rolling for a second or two in order to straighten the van out, before gently applying them again to keep the speed to a crawl. I repeated this process all the way down the mountain. I don't remember hearing or feeling the buzzing of the ABS.

This got me thinking about ABS....

What does the ABS do when in 4x4? The computer doesn't know I have 4x4. What happens when I have the front and rear axles locked together (transfer case in 4x4)? What happens if I have a locker on the front diff?

Is it better to descend nasty steep slippery hills in 2WD with hubs unlocked so the ABS can properly engage the wheels individually?



This is a 2005 E-Series (without RSC).

 

[arctictraveller]

Sorry, but i cant answer your question, but i can tell you i really dislike ABS. Mine is disabled on purpose because i want to be able to lock the brakes if needed. More than once the ABS has released the brakes when i wanted them locked in the dirt so i disabled it. If i want the wheels to turn i can modulate the brakes as needed.

 

[Big_ern_101]

The truck ABS definitely knows the status of 2WD vs 4WD since that data is communicated to the ABS module. What it does with that info ?!?! unknown.

Would be easy enough if a guy wanted to to use the the 4WD status indicator switch on the van transfer case to disable the ABS when in 4WD mode by interrupting power through a relay.

I did some 4WD driving this weekend with my 06 E360 in the snow, wasnt too bad on the ABS brake chatter but this thing is pretty comically different than how it left the factory. If we get some more snow its tempting to pull the ABS fuse and see if it stops much better with the ABS disabled.

If a guy really wanted to suffer he could swap the van ABS module for an early year superduty ABS module and get the selectable modes that the truck had, but this seems like an awful lot of horsing around for minimal gains.

 

[moorefc]

Have a friend that lives outside of Moab. He had an experience with an earlier Explorer in 4WD. Going down a steep slope it would not stop...Almost went off a cliff, except for the emergency brake that stopped it....The ABS kept releasing...


Other thought; Quadvan John once described using chains for both mud and snow.....4WD is great until the coefficient of friction is exceeded!

 

[arctictraveller]

Almost went off a cliff, except for the emergency brake that stopped it....The ABS kept releasing...!

Thats exactly why mine is disabled…