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Unread 09-07-2008, 10:25 PM   #1
bulldog
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Default VSC Disable on Pre 2008 4Runners

So I had a look at the 2008 4Runner wire diagram. It seems that they have a new VSC ECU that allows you the just push a button to disable VSC.

I have always been somewhat irritated at tiems that you are not able to disable VSC without locking the center diff. SOrt of what is the point of having a torsen limited slip center diff and not really be able to use it. Those nice sandy beaches and desert high speed runs, will so much more fun without VSC and an open center diff.

So before I go on, do note that I have not been able to fully test this mod. Also note that this mod is for 4WD 4Runners only, not sure of Tacos or FJCs. I will report back over time to see how it pans out. At least it seems the electronics side is figured out.

The 4WD ECU controls the transfer case to go from 4Hi to 4Lo, lock center diff and also on V6s to go from 2Hi to 4Hi. The transfer case has various switches in it so the 4WD ECU knows whether it is 4H or 4L, center diff locked or not, etc. It also uses these switches to stop the shifter motors from moving to far and damaging the transfer case, so be very careful not to mess up any wires. See caution in attached PDFs.

Looking at the wiring diagram and there is a wire that connect to the VSC ECU from the 4WD ECU and the transfer case. This allows the VSC ECU to know when the center diff is locked and to turn off VSC. This is basically the wire to hack into and fool the VSC ECU that the center diff is locked when it is not. So basically disabling VSC without triggering any error codes in the system.

There is a sensor in the transfer case that is connected to the wire. So when the center diff is locked the sensor will ground the wire. This will in turn trigger the VSC ECU to turn off the VSC in the vehicle and the fun can start.

See 45vsc pdf for the VSC wiring diagram, I highlighted the CDL wire. CDL=center diff lock.

So first things first. The 4WD ECU is located under the glove box, inside the black bottom panel. There is one screw to undo and 4 clips, so just pull the panel towards the passenger seat once the screw is undone. Before going further make sure the ignition is off, and if you feel the need pull the 4WD 20A fuse in the fuse box on the side of the steering wheel.

You will now see the 4WD ECU screwed to the panel, pic below. Ignore some of the wires as it is for my ham and GPS.


See the i740001 pdf for the wire that needs to be tapped into. Marked it in the PDF.

The wire is located on the plug marked with the red circle. It is the red wire with the blue stripe (or whatever they call the funky blue color). Before unplugging the wires, make sure there is no power to the ECU, it might go ape if there is power.




Continued in next post..........
Attached Images
File Type: jpg ECU-location.JPG (258.9 KB, 75 views)
File Type: jpg 4WD-ECU.JPG (135.0 KB, 64 views)
File Type: jpg Diff-Lock-wire.JPG (229.6 KB, 65 views)
Attached Files
File Type: pdf 045vsc.pdf (160.0 KB, 91 views)
File Type: pdf i740001.pdf (109.7 KB, 75 views)
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Unread 09-07-2008, 10:38 PM   #2
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Take some of the isolation of the wire and solder another wire to it. You can use a wire tap as well, but I prefer to solder and not damage the original wire. Now just tape up the area where you tapped in.

Plug everything back to together and put the panel back. Run the spare wire out to an area where you want to put a switch. Before doing anything else, test to make sure everything looks OK.

Using a multimeter test the voltage on the wire that was tapped into the CDL wire. With the ignition on there should be around 10V+ on the wire. Now push the center diff lock button and the voltage should drop to less than 2V. Unlock the diff again. With the ignition on just ground the tapped wire. Only the VSC off light should come on in the instrument panel.

Now connect the wire to a switch with the other end to a good ground point. Every time you close the switch the VSC off light should come on and VSC should be disabled. When open the switch VSC will be enabled again.

The center diff lock light should not come on with the switch closed.

Time for some fun driving using the limited slip center diff, and no trhottle cuts or VSC braking a wheel. Basically the electronic nannies will be off. This mod should not affect ATRAC, but since your center diff is open it will still send power back to front (so not that effective in slow rocky climbs). Either way good to test and see where it is useful.

Obviously do this at your own peril. There should be no issues, but it has not been thoroughly tested. So who knows if there are weird side effects. Either way easy mod to undo as you cut the wire and isolate it (that is if something doesn't get blown up in the process )

In the mean time happy wheel spin Hopefully this will allow me to do proper donuts at Pismo. Should be great fro you V6 guys with 2WD and no VSC = great donuts on the beach.
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Unread 09-26-2008, 02:52 PM   #3
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Just some feedback on this mod.

I was asked to see what happens if I leave the switch on and turn of the ignition. Basically the 4WD ECU gets confused and the diff lock light flashes, if I leave the switch on and turn the ignition off and on again.

If the ignition is already on and I flip the switch on, only the VSC off light comes on and the center diff lock light stays off.


So I would say the mod is intended to be used only with the ignition on, and not when you turn it off or change state (lock diff or 4H-4Lo, etc).
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Unread 10-13-2008, 11:05 AM   #4
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I tested the mod on the V8 on the dunes at Pismo this weekend. The throttle doesn't back down with the mod, even while doing donuts. However I was still able to hear traction control kick in at times, couldn't feel it form the cabin though.

It felt like I was able to do donuts a bit better with the center diff open than closed No bogging down as with the VSC on.

Didn't have the oportunity to do fast enough high speed runs with turns to see how it behaves.

I think the next real tests will be a snow run and a high speed desert run, where this mod will probably be the most useful
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Unread 11-27-2008, 10:05 AM   #5
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I finally got the Holy Grail of this mod...

As you may know this mod allows for VSC off, center diff unlocked operations while in 4wd. What was missing is the ability to run 2wd VSC off. I got it

To use 2wd VSC off is strictly a procedural variation of the existing mod.

The following in conjunction with the mod gets you 2wd w/ATRAC and no VSC:

- Select 4hi and allow it to engage.
- Select VSC off via the installed switch
- Select 2wd. Feel for the telltale 'normal' light thump as it reverts to 2wd. You are now in 2wd w/no VSC and fully functional ATRAC.

NOTE:- Both 4wd indicator lights will flash, the VSC off light will be steady. I drove like this and did the cycle many times with no ill effects. I did two, full 360+ donuts too

- Before shutdown or reselecting 4wd shut the VSC off switch to off (ungrounded position).


EDIT: I will also add there's no audible evidence that in it's "state of confusion" it attemping to do any mode changes. If you listen carefully you can hear relays clicking under the glovebox when the 4WD is attempting to change modes. When driving in 2wd or 4wd with the added VSC off switch in use I hear no clicking.

Enjoy
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Unread 01-13-2009, 04:49 PM   #6
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I follow the directions and I have came to a problem. The Red wire with blue strip is different on the GX. I hav an solid red wire and try grounded that. It didnt work. I need to get a volt meter so I can find theright wire for this mod. Any ideas?

My ECU number is different than a 4Runner



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Unread 01-13-2009, 10:14 PM   #7
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I finally got it! For the GX its the Green wire w/ white strip right next to the Violet wire. There is an open space in between the two!

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Unread 01-14-2009, 04:50 PM   #8
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Quote:
Originally Posted by bulldog View Post
There is a separate VSC ECU. The wire you tap in sends a signal from the 4WD ECU to the VSC ECU that the center diff is locked. The VSC ECU then disables VSC.

The dash light should come on to warn you that VSC is now turned off, a good thing. So I won't meddle with it. Also it will make no sounds when it turns VSC off.
Take a look at these diagrams and I 90 percent sure that I have the right wire.
Legend
B=Black W=White Br=Brown
L=Blue V=Violet SB= Sky Blue
R=Red G=Greed LG=Light Green
P=Pink Y=Yellow GR=Gray
O=Orange

043cdl vsc may be.pdf

CI__CENTER_DIFF__LOCK_SW_main.pdf
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Unread 01-16-2009, 04:13 PM   #9
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