Some kind of inclination protection???

I

ionlyski

Member
Hey all,
So, I had my 08, 3500 down in Canyon Lands last week. To get to some of our trailheads and campsites, you have to drive these little 4X4 roads. The 3500's got great clearance by the way. You don't really need a four wheel drive for most of these; just slow and careful steering, no problem. Anyway, once in awhile there are dry creek beds that you drop down into and back out of. I started noticing coming back out of one (at very slow speeds or even from a stop) the ugliest grinding sound. We were surprised, assuming at first we were merely losing traction. Later I ruled that out and began to suspect the worst, like maybe the transmission. But then, it happened also, slowly dropping down into one of the washes, when I wasn't really applying any throttle. The common denominator seems to be a steep inclination. Is this a form of antilock brakes coming on automatically?

Thanks everyone. Quite concerned.
Arne
 
jdcaples

jdcaples

Not Suitable w/220v Gen
Are you certain it wasn't "don't let that one wheel spin too much" protection?

Dick (autostaretx) once called it sneaky braking and it's my favorite description.

-Jon


Re: AWD options orrr... driving in varied conditions...


--- In sprintervan@yahoogroups.com, "Cindy" <jazzmals@...> wrote:
>
> ... There is some type of traction
> control on these rigs. Is it limited slip for you guys in the know?
> Whatever it is it works pretty well!. You can't floor it and get by
> on pure speed, it will cut power to the spinning wheel so you get a
> kind of jerky, slow forward movement but it does go.

It's not limited slip (in terms of a turns-limiting rearend),
it's sneaky braking.

The Sprinter monitors the rotational speed of all four wheels.
If it thinks you're spinning a rear wheel, it limits the engine
speed, and applys the -brakes- to the spinning wheel.
That causes the differential to transfer torque to the non-spinning
wheel, and (hopefully) off you go.
There should be a light show on your dashboard during this.
(it's in the owner's manual).
You also have a switch to allow you to -override- this action,
should you need to.

have fun
--dick
​
 
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I

ionlyski

Member
Hi Jon,
Well, yeah on the one hand, that's kind of what I was wondering. Except, what's your take on it happening while I was braking (at very slow speed) dropping down into the creek wash? It seems that an antilock brake might have been engaging, not the engine automatically "braking". So, could there be antilock braking happening when spinning the wheel slightly, going up a very steep incline?

And, what's this switch to turn such a system off? I hate automation anything.

Thanks,
Arne
 
jdcaples

jdcaples

Not Suitable w/220v Gen
I agree with Simon's take on things.

I think you might be driving the wrong vehicle if you hate automation (everything). :)

The transmission control module knows the inclination (uphill gradient) as well as being able to access wheel speed... the ABS is a major player under some conditions, too. Here are some StarMOBILE screenshots of the data available to just these two ECUs.

-Jon
 

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220629

Well-known member
Do the NCV3's have an ASR switch? If yes to that, I'd try switching the ASR off next time you're in those conditions. It should work to minimize some of the computer responses and resulting noises. If that makes your Sprinter less effective in the conditions then just switch the ASR back on. As far as I know the ASR switch does not switch off the ESP though.

On my 2004 the dash lights come on when the computer helps drive, but I didn't notice them right off. Usually when the lights come on you're in situations that require you to be looking at the road and otherwise concentrating on driving. Now that I know to look for them I'm more likely to notice when the light comes on. Hope this does some good. AP
 
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