Active stability control system

[Sandy Paj]

I have just worked out a mod now.

When I flick the gear lever over the gate to +/-, it trips a micro limit switch which then turns off ASC.

So for normal road driving I have the safety of ASC, and as soon as I hit a sandy patch I can easily disable ASC on the fly. No more unwanted computer interference.

Also means I can steer with the rear when required

Will post up details with photos when I get the chance.

[Dude]

Good for drifting

[old Jack]

Is it using the same principles as the ASC OFF when centre diff is locked in 4Hlc and 4Llc mode I posted a few weeks ago?

cheers, old Jack.

[Sandy Paj]

Hi Old Jack,

I searched through your recent posts and couldn't find the one you are referring to.

But from the info you have given, it is probably a similar method.

Essentially you are tricking the ASC computer into thinking the transfer is in low range, which cancels the ASC regardless of vehicle speed or gear selection.

I was playing with the diff lock engagement route, but it did not work on my car being a LHD model which if you refer to the electrical manual was not available itch a diff lock.

[rammypluge]

This is a really interesting thread. Did the NM have ASC, TC and CANBUS, or if not when was it introduced?

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[Darwiniandude]

Was introduced with the NP, not the NM. I believe the late 2003 3.8L NP was the first of the petrols, it is drive by wire (no throttle cable) which is required for ASC. 3.5L Early 2003 NP doesn't have these goodies. I think the diesel got it in around the same time but not sure, as I have petrol + lpg.

[rammypluge]

Hi, thanks, sorry for late response, i forgot i turned a heap of notifications off.

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[KieranH]

Originally Posted by pauld
The ASC off switch also changes the TC in that the TC will only use brakes, not cut engine power.

One of the most useful things I've read on this forum so far, really good to know. "


I don't think TC cuts the engine power anyway, no matter what mode you are in. It just brakes the spinning wheel so that the power goes to the opposite side wheel and is not lost as wheelspin.

Only the ASC cuts power, AND applys brakes diagonally to straighten the vehicle.

I see this thread is quite old, but don’t the diffs control the power distribution left and right where there are no lockers in place? I’m fully unlocked in my NT, and every time I’ve been stuck in sand it’s because all the power is being sent to the two wheels (one front, one rear in 4Llc) with the LEAST traction to try to compensate for that very lack of traction. I haven’t seen TC help this situation, although ASC has always been off (not sure if that changes how TC operates). This is why people put lockers in right?

Might have to go out and get stuck in some sand and try out the different settings. I haven’t been stuck in sand for a long time since I worked out how to use tyre pressure properly 😬

[old Jack]

I see this thread is quite old, but don’t the diffs control the power distribution left and right where there are no lockers in place? I’m fully unlocked in my NT, and every time I’ve been stuck in sand it’s because all the power is being sent to the two wheels (one front, one rear in 4Llc) with the LEAST traction to try to compensate for that very lack of traction. I haven’t seen TC help this situation, although ASC has always been off (not sure if that changes how TC operates). This is why people put lockers in right?

Might have to go out and get stuck in some sand and try out the different settings. I haven’t been stuck in sand for a long time since I worked out how to use tyre pressure properly 😬

Hi Kieran,

You are correct in that open front and rear differentials will send the drive to the wheel with the less load, what traction control does is sense the unloaded wheel that has no traction, and applies brake force to stop the wheel from spinning, this action then changes how the differentials are distributing power between left and right. Drive power is then directed to the unbraked wheel and that wheel will become driven. The system on the Gen 4 Pajero works very well but only for a short time, to extend the length of TC operating time the ASTC ECU will cut engine power when a excessive accelerator is being applied and the drive force on the spinning wheel is greater than the amount of brake force that the HBB can safely apply. The TC system will shutdown if it is used for an extended period in high slip conditions, this is prevent overheating and damage to the system.

From the Technical Manual;

The Active Stability and Traction Control System (ASTC) is installed.

• The Active Stability Control System controls four wheels brake force independently and also reduces engine power to manages spin or drift-out when driving near to vehicle limits.
• The Active Traction Control System controls four wheels brake force independently and also reduces engine power to prevent excessive wheel spin and enhance vehicle stability on slippery surfaces. It also improves driving ability on poor surfaces to apply brake force to spinning wheel. The effect is as well as differential lock.
• Fail-safe function ensures safety is maintained
• Improved serviceability
• To shorten the lines and enhance data transmission reliability, communication with other ECU is performed over a CAN (Controller Area Network).

Low tyre pressures and maintaining some momentum are the secret to reducing the incidence of bogging in soft sand.
If you start to slow down and the wheels start spinning then ease off the accelerator slightly and wait a few seconds until the wheels regain floatation and stop spinning. With practice, you can feel when the vehicle has responded and then gently apply more accelerator to increase momentum. It is counter intuitive to back the accelerator off when you are starting to slowdown and are getting wheelspin, but this does work.

OJ.

[nj swb]

A standard open diff will always send the same amount of torque to both output shafts.

When one tyre receives enough torque to overcome its traction, and begins to spin, the diff only sends enough torque to make it spin - and the opposite tyre receives the same amount of torque.

When the TC system applies the brake on the spinning wheel, the diff must send more torque to keep that wheel spinning against the brake - and the opposite tyre also receives more torque.

Offroad, when a front wheel lifts, it can only spin if a wheel at the rear is also spinning - and no spinning equals no traction control. With no resistance, the lifted wheel is receiving essentially no torque - so the front wheel on the ground is also receiving no torque, and the vehicle is effectively in rear wheel drive.

Lock the front diff and the front wheel on the ground can drive again - which is why a front diff lock can make such a huge difference off road.

[Jasonmc73]

A standard open diff will always send the same amount of torque to both output shafts.

When one tyre receives enough torque to overcome its traction, and begins to spin, the diff only sends enough torque to make it spin - and the opposite tyre receives the same amount of torque.

Never looked at it like that
I'll be a genius one day
So that means if it's taking 200Nm to do a burn out, break traction, the one not spinning is still receivng 200nm at the other wheel?
The torque sent to the ground, is governed by path of least resistance but equal on both sides?

[nj swb]

So that means if it's taking 200Nm to do a burn out, break traction, the one not spinning is still receivng 200nm at the other wheel?

By Jove, I think he's got it!

The torque sent to the ground, is governed by path of least resistance but equal on both sides?

I think you've explained it better than I did.

[Jasonmc73]

By Jove, I think he's got it!



I think you've explained it better than I did.

Well bugger me,
So the only reason my wheel with traction loses drive is the other wheel has governed the torque to not much at all, so i need to grab hold of spinning wheel with both hands so it has more resistance & my other wheel will then have more torque, enough to overcome the static enertia is it?
I now drive on.

I'm gunna give that a crack