Finishing up my version of the VSC disable mod

[robtmc]

6/6/14 1811 hours my time: Please read the update posted at the bottom.

Did tons of reading on disabling the VSC and reviewing schematics for the 2007 4Runner.

Decided I did not like two things about the way the mods were done: had to be manually switched off or would cause havoc next time the engine was started (drive the VSC ECU crazy). Did not want to use a toggle switch or modify the factory VSC off switch from momentary to on-off. Basically wanted an OEM like function.

After much study of the wiring and possible relay arrangements, came up with a three relay array that uses the momentary 2008-2009 VSC off switch to turn on the relays and kill the VSC, and the CDL lock momentary switch to provide a ground pulse to turn things back off.

The circuit also is set back to off when power is removed, so it cannot be left on accidentally like an on-off switch. What seems to be nice is the system is not confused if I have it in VSC defeat, switch to 4WD, and hit CDL lock. That opens the relays and enables the CDL lock same time.

Took a bit of wiring jiggery pokery to tap into the power I needed and the dash lights. I used the unused connectors for the 115V convertor (+12V) and the RSCA (dash lights) or whatever that thing is. The CDL momentary ground came off the #3 wire for that switch. Tapped into the VSC ECU Pin 27 line down at the kick panel to avoid cutting wires in the engine bay. That is the wire the original VSC defeat trick came from. It is no more than a signal from the 4WD ECU to the VSC ECU that the CDL actuator has moved.

 

[BlackWorksInc]

Wiring diagrams and explanations are coming of functionality I am assuming? This has piqued my interest.

 

[robtmc]

Wiring diagrams and explanations are coming of functionality I am assuming? This has piqued my interest.

Very soon. Want to clean up the circuit drawing from my somewhat shorthand version.

Did the wiring mockup on a circuit simulation program to prove my madness would work. Have an Autocad drawing of the Radioshcak relays I used in position to guide my wiring. Will include part numbers. The translucent goop is RTV over the solder connections for a poor man's potting compound. For once, I waited until making sure it worked.

Yesterday finished connectorizing and loosely connecting it all to the vehicle. Amazed my usual "aw shucks" or two did not show up for a change.

Pic of most of the wiring prior to hopefully tucking it all back inside the dash this afternoon:

The 115V inverter connector is on the left with +12V switched tapped in. Middle is the RS*** whatever with the dash light connection. CDL switch is hanging down with the #3 wire tapped with the white wire. Ground and VSC Pin #27 wire are hanging out the fuse access opening.

 

[BooRad06]

Is there any reason your VSC off Mod would not work with the V8's? Any plans on testing?

 

[robtmc]

Is there any reason your VSC off Mod would not work with the V8's? Any plans on testing?

Have to review the schematics again, but the differences are very minor, I think it would work exactly the same. If you hit CDL Lock, it would go off and revert to locked CDL and no VSC.

Far as testing, before I bolt the dash back, I gave it another power on test. Still works. There is plenty of room for the perf board holding the relays. Ty-wrapped up the excess wiring and tucked it all away. Ready for bolt up once I check for pinched wires, another specialty of the house.

Everything still cycles. As a test of whether shutting the defeat switch off while simultaneously switching on the CDL Lock, I reasoned the lock stays actuated if the power is cycled and will still be illuminated when back on.

It is so. Cycles as I was hoping it would. What would happen in 4WD if you hit the CDL Lock button to turn the defeat off was unknown, but it is all good. It goes off and Lock comes on.

Using the CDL Lock to turn it off is not obvious, but this is my truck and I do not like toggle switches.

 

[robtmc]

Update

After doing some more testing while running, it looks like the 4WD ECU may get a bit confused by the defeat being on if you try to go from 2WD to 4WD or between other modes. This may be related to what the originators of the mod found if you forgot to turn it off when restarting.

Does not want to engage. Not a matter of movement as far as I can tell yet, as it will go into 4WD just fine if the defeat is off. Defeat goes on fine once in 4WD. which is what I wanted, an instant VSC defeat without CDL Lock on pavement whether in 2WD or 4WD.

So, it looks like the 4WD ECU get confused seeing the CDL actuator pulled high and refuses to do anything until it goes low. Same-same for going from 4Hi to 4LO or the reverse, or going back to 2WD. Have to switch to CDL Lock (twice if you do not want lock) to get the ECU to cooperate. Figures, Toyota did not program the VSC ECU to be used in this manner, and there is probably no way to get them to reprogram to later software.

On reflection, this behavior does not surprise me, the ECU probably is programed to not allow drive mode changes if the CDL Lock is engaged to protect things from sudden loads. The actuator pin that this mod uses to trick the ECU to turning off VSC is what the main ECU uses to determine if the CDL Lock is engaged. Later years probably had a momentary disengage programmed in while changing modes.

Ah well, I really wanted it for instant 2WD and part time 4WD use, not for when I was switching back and forth.

 

[robtmc]

Test drove today, the widget behaved as it did in the garage with the engine running. 4WD modes will not switch with the defeat enabled. I am certain this is the same case for the mod if it is done with a toggle switch. Still like mine better, for the automatic shutoff with engine shutdown.

Kind of neat flooring it in the gravel and spinning as long as I had the foot down, rather than the two revolution and stop like before.

I have gotten into the habit of only switching 4WD modes when stopped anyway, so being briefly in CDL Lock is not an issue, and the convenience of having the "off" right there is nice. Finished product:

<a href="http://photobucket.com/" target="_blank"><img src="http://i894.photobucket.com/albums/ac148/robtmc/vsc_relay_dash_zpsc59188df.jpg" border="0" alt=" photo vsc_relay_dash_zpsc59188df.jpg"/></a>

Circuit with RS parts. This is by no means a proper circuit diagram, but what I used to lay out my wiring and position the relays on perf board for easiest routing. Methods of connection to other areas are best left to the individual. No way would I want to recommend how to bugger your truck.

<a href="http://photobucket.com/" target="_blank"><img src="http://i894.photobucket.com/albums/ac148/robtmc/vsc_relay_control_zps1922b078.jpg" border="0" alt=" photo vsc_relay_control_zps1922b078.jpg"/></a>

More than happy to answer questions on methods privately. There is another relay array I almost tried that would not use the CDL Lock, but I liked the simplicity of what I did. You would have to hit the VSC switch again anyway.

Biggest issue I have with all this fun and games is not knowing from the dash lights if you are in VSC defeat, or CDL Lock. Same lights. Only way to know for certain if not in 2WD is shut off power and power on again. If lights are still on, you are in CDL Lock. I figure this as a 3WD mod, so no big issue at all.

 

[mightyduck]

Hey, any chance you could repost your circuit pics. They dont appear because of some "third party hosting issues"