Diff lock and Traction Control

[Jimbo2]

I’ve been following with interests the posts on the factory diff lock. Two issues arise, those that want Diff lock and Traction control, and those that want neither.

It appeals to me to be able to turn on the traction control and have a locked diff. According to my owner’s manual the traction control only targets the spinning wheel, so it should have no effect on the back axle while locked. I’m still working out why Mitsubishi decided to not have this option.

Also appealing is to be able to turn off the traction control when on soft sand, I’m not sure of the traction benefits, but I get the argument that the car will get along a lot better without the brakes coming on all the time as the traction control tries to cope with the ever changing wheel movements in the sand.

Though not appealing to me there is also a number of forum members who would like to have the diff locked in 2WD.

I put up this post as a start for discussion, and certainly not as a recommendation for action- we have seen a member recently burn out a brake booster and $1000’s out of pocket playing with this stuff. It’s about the knowledge and understanding of the complex machines we drive.

The search;
Initially, like everyone else I looked at the rear differential lock switch (D120). It has 5 terminals:
· Two for the dash board illumination – they are unlikely to be part of the system!
· An earth.
· And an off and on momentary switch which runs from the earth to the computer via the Off line , or the on line. Therefore unless you are actually pushing the button none of these wires do anything! And if you cut one, then the switch simply would not work, I can see no other effect that is possible. As the switch itself is not active except in that moment when the diff is activated or deactivated.
The momentary signal tells the computer 2 things; it tells the computer to turn off the traction and stability control, and also to activate the Diff lock system.

So how does the diff stay active then?
E118 shows this. Power comes in from the switch via the computer at 2. This starts the pressure pump, and at the same time closes the solenoid valve. Pressure builds up flows through a one way valve and activates the locker. (FIG2). Pump switches off and the stored pressure holds the locker in the locked position.

Meanwhile the Diff lock detection switch E 116 activates and sends a signal to the computer that all is well.
Lacking further instruction the computer maintains the diff lock signal at 2 and continues to hold the traction control at bay.
Push the off button, and the computer simply stops the 2 signals, the solenoid unlatches, lets out the pressure and the diff unlocks. The system returns to normal.

Turn off the ignition and the system simply resets.

So to have diff lock and traction control it’s a case of activating the diff lock without the computer knowing, this means separate power to the pressure pump system, and. Shouldn’t be that hard to do, the wires concerned are easy to find at the diff end, and are probably quite findable at the console end, given the computer is drawn in the manual as being in the console.

A question arises though- does the detection switch and associated light on the dash actually do anything other than tell the driver the status of the diff lock? If it is connected to the computer in other ways then a means of preventing the signal from the Detection switch reaching the computer and triggering a fault/alarm/meltdown is required.

How could the system be changed?
I think the best way of looking at this is stop thinking of the existing diff lock switch as the diff lock, but think of it in its other purpose- a traction control switch. Let’s say your diff lock failed and had to be removed from the car. The switch would now simply turn the traction control on and off, and you would have a flashing diff lock light on the dash advising the diff was not locked.

Ok now you install an aftermarket diff lock with a separate switch, the diff lock can be activated at any time, simply by hitting the switch.
So what if the factory diff lock was put on a separate switch in the same way? Then it should work the same. Even better with a 3 position switch and a couple of relays it could be set up as ON - Auto (normal) – OFF
Also I suspect that even if you did not have a diff lock the right connections could be found and a traction control switch could be added.

There are quite a few unknowns here, the effect of signals from the diff lock detection switch on the computer, are there programs in the computer that cause bad things to happen trying to compensate for the system not having the feedback it expects? Finally, why did Mitsubishi set up the system the way they did anyway, was there a problem they were addressing, or was it simply a decision made by a technician who had limited 4x4 experience?

Would I do this on my car? Unlikely, its 6 months old and I would like to keep my warranty.
Any way enjoy and please comment.If best go and do some work instead of thinking about the car!

If you want better quality than the Attached diags, the originals are available on this link: http://faq.out-club.ru/download/paje...3/index_M1.htm

[Quadcam]

You are over-thinking the issue. If you want traction control and the diff lock you break the request and lock signals at the ASTC unit. It is described in threads in the NT or NS sections.

Similarly, if you want to disable the traction control you basically could do the opposite at the ASTC unit (use the same inputs but ground them so the ASTC thinks the diff is locked).

[Quadcam]

The main problem in sand is the stability control system cutting engine power. The ASTC Off button also inhibits traction control by engine power reduction, which is the killer in sand (but allows traction control by wheel braking).

When I originally got my Pajero I was sceptical of the traction control by braking having enough effectiveness. However, an test in 2wd with one wheel on wet grass and the other on bitumen quickly banished that concern. However, while the TC effectiveness is not in doubt there is always the question of overheating the fluid and/or brakes so it is good to have the diff lock option with or without the TC.

[Sandy Paj]

I will be looking at doing the same thing shortly - will post my results.

I don't want any traction control when driving in soft sand.

I know some people disagree with disabling traction control, but when cross cresting dunes you frequently have one or more tires in the air. The standard system detects these 'slipping' wheels and applies the brakes. I don't ever want to brake, I want to maintain momentum.

My other simpler idea is to remove (or add a switch) the buzzer behind the dash, and when going off road I will remove the two relays near the battery.

This buzzer goes off continuously when the relays are removed (after about 10 minutes).

This has the additional benefit of the bypassing over-speed alarm fitted (I assume it is the same buzzer). The speed cameras flash at 140kph here, the over speed is a fixed 120kph. Not sure if Oz spec Pajeros have this.

[pauld]

The only wheel braked is the one in the air with no traction. If no diff lock (eg front) then if you disable TC the power will be delivered to the one in the air with no traction (in the situation you described) instead of the one that is in the sand and could give you drive.

Diff lock rear with TC enabled should be unstoppable in sand, better than twin lockers as steering is still free and front wheels rolling independently.

[Jimbo2]

You are over-thinking the issue. If you want traction control and the diff lock you break the request and lock signals at the ASTC unit. It is described in threads in the NT or NS sections.

Similarly, if you want to disable the traction control you basically could do the opposite at the ASTC unit (use the same inputs but ground them so the ASTC thinks the diff is locked).

Hi Quadcam
Thanks, found the right thread now.
I don't mind "overthinking", I would rather understand the workings of something I may fiddle with, even if others have followed the same path, I've had plenty of instances where the "tried and true" method proved to be not the best solution.
It appears the wires you are breaking are between the Transfer ECU and the ASTC ECU is that correct?
With Thanks

[Quadcam]

Hi Jimbo2, overthinking was probably not the correct word, I also like to understand how things work. Like you, I initially thought to try to do it at the diff lock ECU but eventually realised it was much easier (and more effective) to achieve at the ASTC ECU.

The wires of interest are between the diff lock ECU and ASTC ECU. They need to be intercepted at the ASTC ECU for the dash lights to work correctly. The diff lock ECU signals the request and lock confirmation to the ASTC with the lock light output. The other wire is the physical lock switch at the diff. Either wire by itself will inhibit the traction control so both must be intercepted to have traction control & rear diff lock.

If you ground the lock switch wire by itself (ie, without a corresponding request from the dash switch) the diff lock light will flash and traction control will be inhibited.

[chutsy33]

Hi All, I to would like a simple way to turn off the stability and traction control systems. If I run my NS manual up the creek here ( no rain for 2yrs ) in High 4 the TC keeps on braking wheels until I have lost any momentum I have. If I keep it buried it will stall the engine after giving the clutch a good frying.

[outbackogre]

Having recently completed a crossing of the Simpson in an NP without traction control or diff locks, I'm not sure I'll ever need them. Mind you my wheels didn't lose contact with the ground so it wasn't the sort of conditions for which TC is ideal (ie, cocking a wheel). It sure would have been a nuisance to have TC/ESC cutting power to the engine. I guess those with later models don't have the option of no TC/ESC.

[crazymagna]

Hi Jimbo2, overthinking was probably not the correct word, I also like to understand how things work. Like you, I initially thought to try to do it at the diff lock ECU but eventually realised it was much easier (and more effective) to achieve at the ASTC ECU.

The wires of interest are between the diff lock ECU and ASTC ECU. They need to be intercepted at the ASTC ECU for the dash lights to work correctly. The diff lock ECU signals the request and lock confirmation to the ASTC with the lock light output. The other wire is the physical lock switch at the diff. Either wire by itself will inhibit the traction control so both must be intercepted to have traction control & rear diff lock.

If you ground the lock switch wire by itself (ie, without a corresponding request from the dash switch) the diff lock light will flash and traction control will be inhibited.

Trying to get it right here, if I interrupt the two wires (that was used in the other thread to keep the TC on with diff) and ground them they will work as a TC off switch?
Can you explain how do I gound them? Electric circuits aren't my thing but I can follow instructions.
P.S. I don't have a factory diff lock.

Thank you...

[Hugh]

I’ve been following with interests the posts on the factory diff lock. Two issues arise, those that want Diff lock and Traction control, and those that want neither.

It appeals to me to be able to turn on the traction control and have a locked diff. According to my owner’s manual the traction control only targets the spinning wheel, so it should have no effect on the back axle while locked. I’m still working out why Mitsubishi decided to not have this option.

Also appealing is to be able to turn off the traction control when on soft sand, I’m not sure of the traction benefits, but I get the argument that the car will get along a lot better without the brakes coming on all the time as the traction control tries to cope with the ever changing wheel movements in the sand.

Though not appealing to me there is also a number of forum members who would like to have the diff locked in 2WD.

I put up this post as a start for discussion, and certainly not as a recommendation for action- we have seen a member recently burn out a brake booster and $1000’s out of pocket playing with this stuff. It’s about the knowledge and understanding of the complex machines we drive.

The search;
Initially, like everyone else I looked at the rear differential lock switch (D120). It has 5 terminals:
· Two for the dash board illumination – they are unlikely to be part of the system!
· An earth.
· And an off and on momentary switch which runs from the earth to the computer via the Off line , or the on line. Therefore unless you are actually pushing the button none of these wires do anything! And if you cut one, then the switch simply would not work, I can see no other effect that is possible. As the switch itself is not active except in that moment when the diff is activated or deactivated.
The momentary signal tells the computer 2 things; it tells the computer to turn off the traction and stability control, and also to activate the Diff lock system.

So how does the diff stay active then?
E118 shows this. Power comes in from the switch via the computer at 2. This starts the pressure pump, and at the same time closes the solenoid valve. Pressure builds up flows through a one way valve and activates the locker. (FIG2). Pump switches off and the stored pressure holds the locker in the locked position.

Meanwhile the Diff lock detection switch E 116 activates and sends a signal to the computer that all is well.
Lacking further instruction the computer maintains the diff lock signal at 2 and continues to hold the traction control at bay.
Push the off button, and the computer simply stops the 2 signals, the solenoid unlatches, lets out the pressure and the diff unlocks. The system returns to normal.

Turn off the ignition and the system simply resets.

So to have diff lock and traction control it’s a case of activating the diff lock without the computer knowing, this means separate power to the pressure pump system, and. Shouldn’t be that hard to do, the wires concerned are easy to find at the diff end, and are probably quite findable at the console end, given the computer is drawn in the manual as being in the console.

A question arises though- does the detection switch and associated light on the dash actually do anything other than tell the driver the status of the diff lock? If it is connected to the computer in other ways then a means of preventing the signal from the Detection switch reaching the computer and triggering a fault/alarm/meltdown is required.

How could the system be changed?
I think the best way of looking at this is stop thinking of the existing diff lock switch as the diff lock, but think of it in its other purpose- a traction control switch. Let’s say your diff lock failed and had to be removed from the car. The switch would now simply turn the traction control on and off, and you would have a flashing diff lock light on the dash advising the diff was not locked.

Ok now you install an aftermarket diff lock with a separate switch, the diff lock can be activated at any time, simply by hitting the switch.
So what if the factory diff lock was put on a separate switch in the same way? Then it should work the same. Even better with a 3 position switch and a couple of relays it could be set up as ON - Auto (normal) – OFF
Also I suspect that even if you did not have a diff lock the right connections could be found and a traction control switch could be added.

There are quite a few unknowns here, the effect of signals from the diff lock detection switch on the computer, are there programs in the computer that cause bad things to happen trying to compensate for the system not having the feedback it expects? Finally, why did Mitsubishi set up the system the way they did anyway, was there a problem they were addressing, or was it simply a decision made by a technician who had limited 4x4 experience?

Would I do this on my car? Unlikely, its 6 months old and I would like to keep my warranty.
Any way enjoy and please comment.If best go and do some work instead of thinking about the car!

If you want better quality than the Attached diags, the originals are available on this link: http://faq.out-club.ru/download/paje...3/index_M1.htm

Gday Jimbo2,

Do you think it is possible to use the wires at the back of the diff lock switch to add anotrher switch to simply turn off the ABS???

Cheers

[Pajbus]

I get crucified every time buy I haven't made mention for a while so here goes.

I made a simple patch harness that I connect into line with a front ABS wheel speed sensor and turn it off.
Or before I had the harness ( out of a triton wreck to get the correct connector) I/we (all my mates) just disconnect the front left wheel speed sensor, a two second job when lowering tyre pressure and Fraser, Moreton, Stockton and any other place I've been now give me ZERO trouble.

reconnect when airing up and turn the ignition off and on and no codes
are stored and no expensive harness has been played with.

Simple answer is usually the best.

Never have another issue since.

Without electronic assistance......LOVE THAT CAR. !

[Sandy Paj]

Been meaning to post this for a while.

Just to prove there is more than one way to skin a cat...

I installed a micro switch under the cover to the tiptronic gearbox selector thingy (don't know the proper Mitsubishi lingo for it).



Now when I push the gear lever over to the +/- gate, the micro switch is closed.

This sends a signal the the computer that the centre diff is locked. And whalaa, the traction control is completely turned off until the ignition is switched off and on again.

It would be equally possible to make this a 3 way switch. It could be:

* centre diff actual position (normal driving)
* centre diff simulated closed (what I have, for soft sand)
* centre diff simulated open (to allow locked centre diff and retain all traction aids)

I have no need for the third option but for people that do different driving to me it may be useful.

I wired the switch in such a way that if I ever want to sell the car I can remove the switch and just join two spades together and it is back to stock.

I have been using this for about 12 months now and newer had any problems at all. It is great from turning off traction control in a hurry, like when I need to take some sand short cuts on the way home (I live in a desert, if it is not bitumen it is sand).

Hope this helps someone to gain better control over his traction control issues.

[Jimbo2]

Trying to get it right here, if I interrupt the two wires (that was used in the other thread to keep the TC on with diff) and ground them they will work as a TC off switch?
Can you explain how do I gound them? Electric circuits aren't my thing but I can follow instructions.
P.S. I don't have a factory diff lock.

Thank you...

I tried this method for turning the system off, but disconnected the ground wire when I got unexpected outcomes when I tried to use it. From memory sometimes it worked and sometimes it didnt. I used a switch with a LED "on" light in it, and think that the small current from the light may have been effecting the electronics. Have not had the chance to have another look at it.
I suspect my original plan of using the diff lock sensor wire would work better.

[Jimbo2]

This is the tip of a much bigger topic- should the TC ever need to be turned off?
One thing I have noticed is that there are conditions where turning off the TC and ABS is a real advantage. My conclusion is the ABS/TC system has a lot of advantages, but is also quite dumb and in many situations. It simply stops an inexperienced driver getting into trouble, but is a frustration to the experienced driver.
A good example is recently we were negotiating some really loose and steep hills. After much skidding, sliding and having to hit the clutch several times to stop the engine stalling down hill I locked the diff (turning off TC/ABS) after that the decents were a lot less hairy!
Anothet was a long series of water diversions on an other wise good road. As we hit the top of each hump the car would jerk. Turning off TC/ABS was like getting into a different car, it became smooth and settled.