VSC Disable on Pre 2008 4Runners

[bulldog]

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..........

[bulldog]

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.

[AlexJet]

Thank you Andries. I was looking for this function a long time. Do you know any VSC OFF or TRAC OFF switches I can use?

[bulldog]

Originally Posted by AlexJet

Thank you Andries. I was looking for this function a long time. Do you know any VSC OFF or TRAC OFF switches I can use?

I'm sure you can buy the VSC off switch from the 08 4Runners and use it. Not sure if that switch will stay in position or whether it is just a push/hold type switch. I'm just using a simple toggle switch, as I'm out of room on the OEM switch slots.

[POCHO8]

Andries: So you are basically doing a Wye splice(tap) to this cable, taking it to the switch and then grounding the other side of the switch to a ground point in the car.

Is this correct?

Thanks,
Phillip

[AlexJet]

Originally Posted by bulldog

I'm sure you can buy the VSC off switch from the 08 4Runners and use it. Not sure if that switch will stay in position or whether it is just a push/hold type switch. I'm just using a simple toggle switch, as I'm out of room on the OEM switch slots.

I'm out of switch saces as well. I thought of some aftermarket switch with VSC or TRAC logo.

[Joel]

Awesome Andries! Now to find a location for another switch..

[bulldog]

Originally Posted by POCHO8

Andries: So you are basically doing a Wye splice(tap) to this cable, taking it to the switch and then grounding the other side of the switch to a ground point in the car.

Is this correct?

Thanks,
Phillip

Yes. Just creating a parallel circuit to the transfer sender. It wont hurt any of the electronics nor trigger an error as it is seen as a normal condition by the VSC ECU, not an error code that will disable it.

Some testing is still called for as to vehicle behavior, but I don't expect any surprises. I just like having the ability to quickly turn VSC on and off when I want/need to.

[rdrunner]

Nice job figuring this out. I'm assuming this would work when in 2WD also? It may sound silly but that's one thing I'd love to have in the 4runner - the ability to run in 2WD with no traction control when I feel like it. It makes for some fun times in snow.

[07 Elephant]

Could a parts number savy person find the part number for the vsc-off switch that the 08 runner has?

I'm going to move the 115v switch - probably to the center glove box close the the outlet.

[bulldog]

Originally Posted by rdrunner

Nice job figuring this out. I'm assuming this would work when in 2WD also? It may sound silly but that's one thing I'd love to have in the 4runner - the ability to run in 2WD with no traction control when I feel like it. It makes for some fun times in snow.

This mod won't work on 2WD models. For starters the 2WD doesn't have a transfer case nor a 4WD ECU. The principal of the hack is that it makes the VSC ECU think the center diff is locked while it is still open.

To make it work on 2WD you need to figure out under which conditions the VSC would be off, and then figure out a way to simulate that without being intrusive on the rest of the system. You can dig in the 2WD wiring diagrams and see if you find an EXI connection on the VSC ECU. This needs to be grounded for the VSC ECU to turn off VSC functions.

Either way we can discuss this in another thread if you like, but lets focus this thread on the 4WD and see how it works and where it goes.

[rdrunner]

I was talking about a 4wd v6 while in 2wd. Sorry I wasn't more clear.

[bulldog]

Originally Posted by rdrunner

I was talking about a 4wd v6 while in 2wd. Sorry I wasn't more clear.

I thought I explained it, but yes it will work on the 4WD V6 as well. It should work irrespective of whether it is in 2WD or 4WD.

[rdrunner]

I see that, thanks. I look forward to trying this sometime soon.

[bulldog]

Originally Posted by bulldog

I thought I explained it, but yes it will work on the 4WD V6 as well. It should work irrespective of whether it is in 2WD or 4WD.

Originally Posted by rdrunner

I see that, thanks. I look forward to trying this sometime soon.

Actually I looked at the wiring diagrams again. This hack might not work in 2WD for the V6s. The reason is that the center diff is actually locked when you are in 2WD.

Best way to find out is to do it and see what happens.

[CJ3Flyr]

Andries, you are a rockstar! Thank-you for sharing.

[07 Elephant]

I have the pt# for the switch, thank you Robert, but these things are not returnable. So can someone with an 08 or someone with access to a switch in the parts bin (my local has to order it) tell us all if the switch is like the dac, were it toggles on or off, or like the diff loc and rsca and how it doesn't toggle and stick in or out. Clear?

[SP Jon M3]

The VSC switch is a momentary switch. It's not a toggle like the DAC switch.

ETID: off topic; Strange, my account got wiped out.. I've made many more posts than 2.. humm.. also my sig is gone.

[CJ3Flyr]

I just completed the mod. In 2wd dash lights are on (VSC & Diff lock). I didn't mess around enough to decide if VSC is working, traction control IS working; I'm assuming it has full VSC. It has all the familiar noises and accompanying reduction in power. The system seems to get confused if you attempt to change from 2HI to 4HI with the switch on.

In 4HI it works as advertised You have an unlocked Torsen center diff and no interference from the VSC; the VSC and Diff Lock light are on. You can definately feel/hear ATRAC doing it's thing. The same deal in 4LO... My advice is to not do a mode change with the switch on. I may retract/ammend that as I learn more.

Andries, you saved me thousands! I was having serious 'VSC-off' envy of the 2008 guys, thank-you!

[Mikestang]

Originally Posted by CJ3Flyr

...dash lights are on (VSC & Diff lock)...

...the VSC and Diff Lock light are on...

Originally Posted by bulldog

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

Sounds like you have a mistake somewhere if the diff lock light is coming on.