VSC/TC Complete Disablement: Yaw sensor interrupt

[bmw325_num99]

As I recently posted previously, I have been trying to find a way to completely disable my VSC and traction control for gravel road private property fun and hoonery. Yes, you can engage 4wd and the center diff lock to disable these things. However, I like to drift a little and 2wd mode in my 2006 SR5 V6 4x4 4runner is the best mode for that. Unplugging the gray plug on the brake reservoir under the hood did not completely disable my stability control. So, after the investigating discussed below I decided to try something new. I have never seen a write-up on disconnecting the yaw sensor inside the car to disable VSC I unplugged the yaw control sensor located near the shift lever in the center console it and this achieved what I wanted. Now, to make disabling the yaw control sensor quick and easy, I rigged up a switch as others have done with the under-hood, gray, reservoir sensor plug documented here.

http://www.toyota-4runner.org/4th-g...c-abs-without-damaging-factory-wiring-10.html

http://www.toyota-4runner.org/4th-gen-t4rs/112855-how-turn-vsc-trac-off.html

http://www.toyota-4runner.org/4th-gen-t4rs/35392-vsc-off-button-2008-v8-ltd-4runner.html#post299186

However, MY switch would be spliced into the yaw sensor in the interior center console. Here is how I did it in about 1 hour once I had all the materials at hand.

Materials

a) A switch/button/interrupter. I used a basic Ace Hardware toggle switch for testing and will soon replace it with the OEM Toyota VSC switch part #84988-35070
b) Two lengths of wire, each about 18 inches in length, stripped on both ends
c) Wire stripping tool
d) Wire cutters
e) Electrical tape
f) Screwdriver (if needed for toggle switch)
g) Socket (10mm)
h) Socket extension, ideally 6 inches or so or more
i) Socket wrench
j) 2-4 Wire connectors/splicers depending on what switch you use



1. Ensure engine is off, key is out and ignition switch is off
2. Open center console storage bin door by lifting up
3. Unscrew the 2 bolts at the bottom of the storage bin

4. Twist, pull, pry yank the center console surround up a little

https://www.youtube.com/watch?v=uB9li4KjueE
http://www.toyota-4runner.org/4th-gen-t4rs/82996-4th-gen-center-console-disassembly-need-help.html

5. Unplug the cigarette lighter and DAC button plugs


6. Open and remove the vertical flapper door/small storage container in front of the shifter by pulling up on it once it is opened. I pressed my finger against the clips/hinges to get it out

7. Unscrew the 4 center console bolts located on either side of the shifter






8. Pull the center console towards the back of the vehicle, lowering the front of the console slightly to clear the 2 pins near the front 2 bolts.
9. Unplug the white shift sensor plug near the front right corner of the shift mechanism


10. Unclip the two clips on either side of the front/bottom of the center console, near the drivers right shin and passenger left shin. Lift the center console out



11. Locate the yaw sensor in front of the shift mechanism. Mine was labelled “yaw sensor” or similar

https://drive.google.com/file/d/0B-U46S3GS9ZoQUV2b3dYRElVZWs/view?usp=sharing

12. Carefully slice the surrounding tape/material that shrouds the 4 wires. I cut this material to about 4-5 inches from the yaw sensor to expose the wiring

https://drive.google.com/file/d/0B-U46S3GS9ZoN3V3YkZaMk9TclU/view?usp=sharing

13. Cut the red wire (not the red and black one) which is the second wire from the end. Other wires might work two but you only need to cut one and I somewhat randomly chose the red one and it worked. Here is a wiring diagram I found but I end up not using it.

http://www.toyota-4runner.org/4th-gen-t4rs/100275-service-manual-download-links.html

14. Use electrical wire strippers to expose wire on each of the two loose ends of the now-cut, red wire.

15. Take one of your two lengths of wires, splice it to the severed and stripped yaw sensor wire on one end and your Ace Hardware toggle switch or what have you

https://drive.google.com/file/d/0B-U46S3GS9ZoYkhkZE1tSFhqNkE/view?usp=sharing

16. Do the same for the other length of wire: Connect one end to the switch and the other to the other loose strand of wire
17. Tape the connections back up on all ends so no bare wire or metal is exposed.
18. Pop out one of the blanks on the center console (assuming you have one). If you want to put the VSC off toggle switch in the factory location near the drivers left knee, you could, but you need more wire.

https://drive.google.com/file/d/0B-U46S3GS9Zob1NyaU1seC1jMU0/view?usp=sharing

19. Route the wired-in switch to the blank space.
20. With the toggle switch on (engaged), test the switch by starting the engine. The VSC/TC lights should go off like a stock vehicle.
21. Press the toggle switch to break the circuit (off) and after a second or two the VSC/TC lights and some others should illuminate, indicating these systems are disabled (and fun can begin)
22. Interior assembly is the reverse of removal.



For posterity, my old posts that describe why the gray-wire-brake-reservoir-unplug mod didn’t work for me:

Short Version: In a 4wd v6 2008-2009 4runner while in 2wd, can you SAFELY go to a gravel road/field/parking lot or similar and completely disable VSC? Then, try to get it to drift/spin out under braking/do a 4wheel-drift and see if the ABS activates or the VSC tries to stabilize the vehicle? Let me know, please...can you spin out/drift completely with no input from the computers or are they still trying to take control? You may hear the ABS pump shuddering or feel the vehicle's path being altered by the computers braking one or more wheels.

Long Version: Here is the background. I love sports cars but sold them to try to merely have 1 vehicle. I chose my 2006 V6 4runner 4WD SR5 as my only vehicle so that I can have fun powersliding/drifting/hooning in fields in 2wd so I can still have some fun and challenging car-control situations. It is no BMW but powerful enough and rear drive that I can theoretically have some fun. [Please refrain from lectures on safety, rollovers, etc. I am good to go there].

HOWEVER, as you all know from the many threads on the subject, ABS and VSC prevent you from having much fun at all in 2wd mode. I unplugged the gray connector near the brake reservoir like so many have done and that did indeed light up my dash with all the warning lights as it should. I was even able to slide around some more than normal which was great. Again, HOWEVER, I swear one or more of these systems is NOT deactivated fully; I still feel and hear the ABS pump kicking on while trail-braking (in the sports car sense, not on an offroad trail sense) and while accelerating out of a turn while powersliding/drifting. This was really frustrating me.

Next, just yesterday, I unplugged the small black connector next to the gray one which did nothing. Also yesterday, I unplugged the very big connector on the side of the brakebooster/reservoir assembly, the connector with the sliding clamp that holds the plug in place. The VSC/Traction lights went off and the ABS light and check engine light came on. I thought "great, this seems different then before" and went for another drive. SUCCESS!! There was no sign of VSC/TC/ABS working so I was having a blast until.....

....The brakes started feeling wooden and weak. I quickly realized the brake booster system had stopped working. I am not comfortable driving this way without the brake booster so I am back to square one. My question up top in the "short version" is to see if the VSC disable button on the 2008-2009 models actually disables everything. If so, I will sell my 2006 for a new model.

I did look into some of the mods offered by the members here but there was no certainty that the VSC and ABS would be completely disabled.

 

[gfluff]

Interesting
What lights do you get on the dash with the sensor turned off?

 

[BlackWorksInc]

This seems like more work than it's worth honestly, not to mention depending on how you have the switch wired you're going to need to rezero the Yaw Rate Sensor every time you renable it.

I would have probably just spliced into the driver's rear wheel speed sensor wire at the junction connector by the driver's kick panel. It's a one-trip system so the moment the sensor is disconnected VSC/TRAC should be disabled and possibly ABS (I can't recall the fail safe chart off the top of my head right now) and when you flip the switch a quick cycle of the key should reset the light.

 

[bmw325_num99]

Interesting
What lights do you get on the dash with the sensor turned off?

Lights that come on: VSC OFF, Low traction light with the skidmarks behind the car, ABS, VSC TRAC

Lights that stay off: Cruise, Check engine and all other lights.

 

[bmw325_num99]

This seems like more work than it's worth honestly, not to mention depending on how you have the switch wired you're going to need to rezero the Yaw Rate Sensor every time you renable it.

I would have probably just spliced into the driver's rear wheel speed sensor wire at the junction connector by the driver's kick panel. It's a one-trip system so the moment the sensor is disconnected VSC/TRAC should be disabled and possibly ABS (I can't recall the fail safe chart off the top of my head right now) and when you flip the switch a quick cycle of the key should reset the light.

It only took an hour for me to do once I had the materials ordered/purchased. This is SO worth it to me; the alternative was to buy a 2nd car to drift around in on dirt roads plus have to take that car to rural roads in WI where I go instead of the much-more family-friendly 4runner. Lastly, this is a comparable amount of time to the dozens of people that rigged up the switch to the brake reservoir sensor which is well-documented elsewhere.

Also, I have not seen any reason to re-zero the sensor. Everytime I start the car up, it behaves normally (assuming I remembered to turn the toggle switch I added back to "on". I am not sure why you think this would be a problem but, at least, its not on my car.

Lastly:

" It's a one-trip system so the moment the sensor is disconnected VSC/TRAC should be disabled and possibly ABS (I can't recall the fail safe chart off the top of my head right now) and when you flip the switch a quick cycle of the key should reset the light"

This is EXACTLY how my method works so its a tie there!

 

[bmw325_num99]

Here is the switch I ordered, probably the same one everyone else ordered. Should arrive this week so I can be rid of the ugly hardware store toggle switch

https://www.ebay.com/itm/322141215677

 

[bmw325_num99]

And a quick video showing its operation. Sorry for vertical orientation!

https://youtu.be/Zw4GJmyoULI

 

[feralcomprehension]

...I have not seen any reason to re-zero the sensor.

I like the sound of this and have a couple questions.

1. On the sensor re-zero- can you say with 100% assurance that the VTS/ect... returns to 100% normal function after you've had it deactivated?

2. Can you please clarify- will the system re-activate once you reconnect the yaw sensor via the switch or is a key-off required?

Thanks!

 

[bmw325_num99]

I like the sound of this and have a couple questions.

1. On the sensor re-zero- can you say with 100% assurance that the VTS/ect... returns to 100% normal function after you've had it deactivated?

2. Can you please clarify- will the system re-activate once you reconnect the yaw sensor via the switch or is a key-off required?

Thanks!

1. How could I tell that it reaches 100% functionality? I will say that the lights stay off, the vehicle drives and feels the same as before, the ABS and TC and VSC behave as they have in the last 9 months I owned the car. Dont know if that helps but I am open to testing per your suggestions.

2. Key off and on is required. The VSC and TC will remain disabled and the warning lights listed in my previous post will remain on until you turn the ignition off and on

Thanks for your interest!

 

[feralcomprehension]

1. How could I tell that it reaches 100% functionality?

Well, 100% could be hard outside of instrumented testing on a special track, but since you like to hoon about on the back roads (and let's face it.. who doesn't?) how about a hard run on a road you know well with VTS active, then deactivated, then active again, and compare runs 1 and 3?

Again, I like the sound of this (VTS steps in quick) and while the idea of shutting it off is appealing compromising it's function when I expect it to work well isn't so attractive.

Thanks!

 

[BlackWorksInc]

It only took an hour for me to do once I had the materials ordered/purchased. This is SO worth it to me; the alternative was to buy a 2nd car to drift around in on dirt roads plus have to take that car to rural roads in WI where I go instead of the much-more family-friendly 4runner. Lastly, this is a comparable amount of time to the dozens of people that rigged up the switch to the brake reservoir sensor which is well-documented elsewhere.

Also, I have not seen any reason to re-zero the sensor. Everytime I start the car up, it behaves normally (assuming I remembered to turn the toggle switch I added back to "on". I am not sure why you think this would be a problem but, at least, its not on my car.

Lastly:

" It's a one-trip system so the moment the sensor is disconnected VSC/TRAC should be disabled and possibly ABS (I can't recall the fail safe chart off the top of my head right now) and when you flip the switch a quick cycle of the key should reset the light"

This is EXACTLY how my method works so its a tie there!

Again it depends on how you've done the cut-off. If you're cutting off a communication line then maybe it's fine. If you're cutting power it could be an issue.

'03 & '04 4Runners are notorious for having finicky Yaw Rate Sensor data, low battery voltage and/or even clearing codes in the system can reset the learned value. Later ones seem to have "fixed" that quirk, how I can't say for sure; but leave a newer 4Runner's battery disconnected long enough and usually it'll need a ZPC again anyways (vs. the '03 & '04's that if you just leave it disconnected for a minute or the voltage drops below about 11.5 or so it seems to "reset").

It's difficult to say IF your Yaw Rate Sensor's calibration is affected or out of whack as it's a relative measurement (hence why you do a ZPC). But if it works for you it works, I'm just pointing out a potential issue; I would rather not have a question of whether or not a sensor is calibrated properly (particularly since you really can't verify it without doing a ZPC so you know for sure) when alternatives exist. Like I said, you'd probably get the same result by simply splicing into the ABS Wheel Speed Sensor on it's way through the firewall to the master cylinder.

 

[mar5168]

If the calibration isn't stored in the sensor itself (which I believe it isn't) then all should be good with zpc. The control unit will not abandon learned zpc because lack of communication on a CAN line, that would be dangerous.

 

[BlackWorksInc]

If the calibration isn't stored in the sensor itself (which I believe it isn't) then all should be good with zpc. The control unit will not abandon learned zpc because lack of communication on a CAN line, that would be dangerous.

Which is why I was thinking that if it's just cutting the communication line to the ABS module then it shouldn't be an issue (it's not on the CAN Bus by the way; uses a direct line to the ABS Module).

As for it storing the data in the Yaw Rate Sensor? Probably not? I can't say for sure, the ABS module could keep the ZPC data or it could be kept in the Yaw Rate and transmitted to the ABS module. My best guess is that the data is kept in the ABS module, but like I said before; in '03~'04 models specifically low battery voltage/interruption caused ZPC to be unlearned/corrupted; hence why I was saying a better option would be to simply interrupt a wheel speed sensor. Particularly since you as a user wouldn't be able to tell if the calibration was somehow skewed as it's not something you can really see.

 

[Bumbo]

Why not just dump the zero point calibration?

It requires no permanent modification to the truck at all.

 

[bmw325_num99]

I have achieved half of the test you asked for, I would say. I drove the 4runner in the rain with everything "normal" (switch on). VSC and TC behaved normally and would step in when I would turn sharp to the right or left from a stop and while accelerating aggressively.

Then, I disengaged the switch for a few miles, probably 5-8 minutes, and did some burnouts and 1-wheel brake stands with all the warning lights on. I returned the switch to normal, shut off the car and drove it again in a few hours, still in rainy conditions, with the switch on in normal mode and the VSC/TC were absolutely still working and engaging and being their normal fun-police self.

What I did NOT test is a long-long duration test to see, as one of you guessed, might affect the ZPC issue differently. I will do this on the way to work on Tuesday which is 29 miles and take over 40 minutes one way. Then we will see if the ZPC issue comes up.

TL;DR - so far so good, switch I rigged up disengages VSC/TC when I want it to and the car still works normal when I leave the switch alone. Will test a longer distance this week.

 

[feralcomprehension]

Very cool. Looks like the ZPC isn't too difficult to do should that be necessary, so either way you'll be covered. Looking forward to reading the results of your longer-term test; thanks for contributing!

 

[mar5168]

Which is why I was thinking that if it's just cutting the communication line to the ABS module then it shouldn't be an issue (it's not on the CAN Bus by the way; uses a direct line to the ABS Module).

As for it storing the data in the Yaw Rate Sensor? Probably not? I can't say for sure, the ABS module could keep the ZPC data or it could be kept in the Yaw Rate and transmitted to the ABS module. My best guess is that the data is kept in the ABS module, but like I said before; in '03~'04 models specifically low battery voltage/interruption caused ZPC to be unlearned/corrupted; hence why I was saying a better option would be to simply interrupt a wheel speed sensor. Particularly since you as a user wouldn't be able to tell if the calibration was somehow skewed as it's not something you can really see.

I believe it is CAN. If memory serves me correct, two of the wires to the yaw sensor are CAN sub bus lines off of CAN-L and CAN-H at the CAN junction. The main bus lines of the CAN junction are fed from the ECM and the Skid Control ECU receives communication identically to the yaw sensor and virtually every other CAN node; CAN bus sub lines from the CAN junction.

If you want to know for sure, probe the yaw sensor connector with a DMM and see if any combo of two wires yields roughly 120 ohms; the impedance between the CAN high and low lines.

This would also mean that either the ECM or Skid Control ECU could store ZPC data, but I can almost guarantee its stored in the Skid Control ECU. It makes absolutely no sense to store safety critical logical parameters in a different control unit. If somebody wants to confirm this, look up Skid Control ECU replacement, I bet it requires ZPC after replacement.

 

[BlackWorksInc]

I believe it is CAN. If memory serves me correct, two of the wires to the yaw sensor are CAN sub bus lines off of CAN-L and CAN-H at the CAN junction. The main bus lines of the CAN junction are fed from the ECM and the Skid Control ECU receives communication identically to the yaw sensor and virtually every other CAN node; CAN bus sub lines from the CAN junction.

If you want to know for sure, probe the yaw sensor connector with a DMM and see if any combo of two wires yields roughly 120 ohms; the impedance between the CAN high and low lines.

This would also mean that either the ECM or Skid Control ECU could store ZPC data, but I can almost guarantee its stored in the Skid Control ECU. It makes absolutely no sense to store safety critical logical parameters in a different control unit. If somebody wants to confirm this, look up Skid Control ECU replacement, I bet it requires ZPC after replacement.

Just looked at the wiring diagram, that's interesting it is on the CAN Bus; not even the dedicated ABS multiplex network.

In any case, like I said if it works it works. But as I said before, if the yaw rate data became modified you wouldn't be able to tell as it's a relative measurement; the only real way you'd know is to do a ZPC everytime. While the chance is probably very small (particularly on '05+ models) that's a margin that can be avoided by disabling another component.

It wasn't condemnation but rather just pointing that out for anyone who would like to disable their VSC this way is all.

 

[bmw325_num99]

Thanks for all the additional background, folks.

I did not get to test it at-length as I had hoped today as I didnt need to drive it far. Next time I take a long drive, I will test it out and report back if there are any ZPC issues or other issues.

My factory "Disable Traction" switch came today, referenced with part # elsewhere in this thread. I was testing it with the ohmmeter and disappointed to find out there is no simple "closed at rest" circuit combined with a "open when pressed" circuit on the switch. The switch as 4 prongs and 2 smaller contacts but no combination of the 6 yeilded the behavior I was hoping (where pressing the switch would momentarily break the circuit.

Instead, I think I will order some generic horn buttons or other momentary switches and try to adapt them to the factory switch so it LOOKS factory from the passenger cabin but inside/underneath the center console, it behaves the way I want with the generic switch. Ill keep y'all posted but any ideas on using the factory switch as a momentary circuit-breaker (switch, not like a fuse of course) would be appreciated.

"GENUINE TOYOTA TRACTION CONTROL SWITCH OEM 84988-35070"
https://www.ebay.com/itm/322141215677

 

[bmw325_num99]

Update:

I turned the switch off to disable VSC/TC for a 1.5 hour drive on Sunday. AS expected, they remained disabled.

Upon restart, the VSC and TC worked normally and they have continued to do so. Conclusion: no Zero Point Calibration needed, at least not on my particular year/model/options/computer setup.

Since the Toyota switch I ordered does not have any "normally closed, open when pushed" setup, I ordered a different switch from Amazon and CruiserHeads 4x4:

CH4X4 Toyota Push Switch VSC Symbol - Amber Led

https://www.amazon.com/CH4X4-Toyota...1FFGOCLVUL&preST=_SY300_QL70_&dpSrc=srch&th=1

I will just toggle the switch on and then off in this circuit i rigged up to disable VSC going forward (just like I do now but right now I have an ugly, generic steel toggle switch in place).