Aurion Traction Control Switch

[DJKOR]

Firstly, as with any modification, the information provided here is is for reference purposes only. I will not be held accountable for any damaged done to your car, yourself, the property of others, or other persons as a result of performing any of the procedures shown here. Modification to the skid control ECU can compromise the safety of your vehicle during emergency manoeuvres or spirited driving.

With that out of the way, since the knowledge on this subject is something to be shared, I will provide the following information that will give you an idea of how the Traction Control system is wired up on the Aurion, and what can be done to override it.

On a basic level, the Skid Control ECU (which is located on the ABS actuator) monitors speed sensors located on each wheel. For the purposes of Traction Control, it will notice when the front speed sensor/s are rotating at a greater amount than the rear sensors and if it detects this, it will cut the throttle to regain traction.

One theory I had was that we could easily override Traction Control if we trick the ECU into not seeing a difference in rotation. Since each speed sensor is basically an AC motor that outputs a waveform, the idea was that if we disconnect the front speed sensors and connect the rear speed sensors in parallel, then the ECU would never see the front wheels spinning.

After sitting on the thought for a bit, the idea was finally tested and the final conclusion was that this is a viable solution. In doing this though, you not only disable your Traction Control, but you also lose your ABS and even VSC in most scenarios. A solution that enables you to switch between enabled and disabled had to be planned.

In the end, an electronic switching solution was desired as this would not only improve switching speed (you ideally would want it to switch instantly so as to not throw an error code) but it would also allow you to integrate a fail-safe that would automatically re-enable Traction Control when your engine is switched off.

To start with this modification, you need to access the wiring harness on the Skid Control ECU. When you have disconnected it and removed the cover, you will be left with this:

The connector has some pin numbers on it to help you figure out which pin is which, and the ones you will be concerned with are as follows:

FL+ : Light Blue, Pin 5

FL- : Violet, Pin 6

FR+ : Pink, Pin 10

FR- : Light Blue, Pin 9

RL+ : Red, Pin 7

RL- : Light Blue, Pin 27

RR+ : Black, Pin 29

RR- : White, Pin 8

Now for the fun stuff. The following diagram is provided as is. If you have difficulty understanding it, then this may possibly not be the job for you. I have utilised a DB15 plug and socket to enable easy connection and disconnection to the control box from the ECU. With the 12v source for the SPST relay on the lower left, if you connect it to a switched +12v source, you can take advantage of the fail-safe automatic switch-on. The switching circuit can be modified to use a 4PDT relay, electronic momentary latching relays, or completely electronic control. It is up to you if you choose to go down that path. The information provided here is what I have done personally and have tested.

So if you are curious...

Mine varies just a little in relation to the TC on/off switch. I have an illuminated push-button with a dual stage press. It basically enables me to combine the NC and NO switches in a single push button. I half-press the button to turn off the TC, and do a quick full-press to re-enable it. For the sake of simplicity though, I have not included those specifics in the above diagram.

On a side note, as of this present time I have only tested switching between the disabled and enabled state while the car is STATIONARY. I'm not exactly willing as of yet to try switching it while the car is moving due to the potential for a minor voltage spike which may not be so good for the skid control ECU.

Edit: Not long after fitting this, I had performed a switching test while driving. To sum it up, yes you can switch between TC enabled and disabled while driving. More details are listed in Post #5 below.

As well, now as my project is fully completed, here is my parts list and current Jaycar pricing. You can save money by either substituting parts or sourcing them elsewhere. This is just to give you an idea of how much it would cost if you went down to your local Jaycar.

1 x Sealed ABS Enclosure - 115 x 65 x 40mm : $8.95

2 x 12V DPDT 10A Power Relay : $7.95 ea

1 x Micro 30A Horn Relays : $6.50

5 x Blue Extra Heavy Duty Hook-up wire : $0.70 metre

2 x 4 Core Screened Professional Microphone Cable : $2.70 metre

1 x DB15 Male Connector - Solder : $1.95

1 x DB15 Female Connector - Solder : $1.95

1 x DB15 Plastic Backshell : $2.45

1 x IP67 Rated Illuminated Momentary Switch Green : $14.50

2 x LED 5MM DIF COM CATH ORG/GRN 70/80MCD : $1.00 ea

1 x 620ohm 1/2 Watt 1% Metal Film Resistors - Pk.8 : $0.46

1 x 1N4004 1A 400V Diode - Pack of 4 : $0.50

Grand Total: $64.06

Edit 2: As per post #34 on the second page, this circuit has received some modification:

You will notice that I have left out the trigger circuit in this diagram. You an either integrate the same one as used on the first diagram or you can use the method Steven has shown. As long as it switches to ground, it will activate the circuit.

[Steven]

As another participant in this mod, I strongly endorse the above switching method to all who partake in this madness. Electronic switching is possible but the path is paved with confusion and migraines.

BTW Daryl, 1.52am posting time?

[DJKOR]

BTW Daryl, 1.52am posting time?

Well... it took me a bit of time to draw that diagram up after getting home at 11:30pm from the Marriott. Realistically, as simple as that circuit is, I made it freehand while I was there and it surprisingly took away my mental power.

[Steven]

The electronic switching arrangement I was talking about - and who knows if it will work once off the test bench and into a car environment...

[DJKOR]

To further add to this thread, in my first post above I stated that switching between Traction Control on and off has only been tested with the car stationary. Now to be realistic, if this were to always be the case, there is going to be in inevitable moment where you accidental switch it with the car moving. So last night I set out to test this.

At suburban speeds of about 60km/h (as indicated by the speedo), switching between TC on and off does not cause the ECU to give any form of response back. At highway speeds of around 80km/h however (though I noticed it can possibly happen around 70km/h), the ECU detects something is going on and will light up the warning light, the traction control light, the check engine light, and the 'Check VSC System' warning message. The lights do however turn off after a few seconds and no error code is logged in the ECU.

If I was to provide a recommendation, I would still suggest that it would be a wiser idea to switch between TC on and off only when the car is stationary. If you must do it while moving, then slowing to 60km/h or below would be what I would suggest. That said, at least you know that if you must change it while on the highway, you probably won't break anything (can't guarantee that though).

To give you an idea:

[Silver-Aurion]

Interesting. I wonder why the ecu doesn't log the error. Also good thread man. Been reading it thoroughly, definitely an Australian first :)

[Steven]

Interesting. I wonder why the ecu doesn't log the error. Also good thread man. Been reading it thoroughly, definitely an Australian first :)

Got my solid state version in and running - however it will not switch the relays if the car is running down on battery as I just found and caused a VSC error (as relay didn't have enough power to fully turn on).

As for why the ecu doesn't log the error, who knows? Right now I'm thankful it doesn't, but perhaps Toyota in their wisdom decided to set up the system so that a minor hickup every now and then wouldn't create a permanent error code and require dealer servicing to correct.

[DJKOR]

Got my solid state version in and running - however it will not switch the relays if the car is running down on battery as I just found and caused a VSC error (as relay didn't have enough power to fully turn on).

As for why the ecu doesn't log the error, who knows? Right now I'm thankful it doesn't, but perhaps Toyota in their wisdom decided to set up the system so that a minor hickup every now and then wouldn't create a permanent error code and require dealer servicing to correct.

I kind of regret not not buying solid state relays in the first place. It would have been nice to just have it all with no moving components. I don't think it will solve the warning light issue at speed mainly because the ECU is made to detect the following fault condition: "Abnormal change in output signal of front/rear speed sensor". I guess though due to the way I have made it, I can build one up when I want to and all I will need to do is just swap the control box. That said, I wonder if it would work with my dual stage switch (which I suspect works in this case due to the mechanical relay lag).

And yeah, I think you're right with regards to the error code. When you switch it, it probably only sees the glitch for less than a second and it is probably waiting to see it for a few seconds at least before logging it.

[Steven]

I dont think solid state relays would work because arent they just high current oversized transistors? No good for a dc signal

[DJKOR]

I dont think solid state relays would work because arent they just high current oversized transistors? No good for a dc signal

Well in the general sense, you could say a solid state relay is basically like a larger transistor when you visualise what it does. But on a more technical side of things, it is quite different. A solid state relay will operate pretty much like a mechanical relay in that you apply power to the input side, and it allows power to flow on the output side. There is no variation in the flow of current like a transistor can provide SSR's have the input and load sides completely isolated via opto-coupling unlike a transistor.

The good thing as well is that you can commonly get ones that have a switching point as low as a few volts. This means that the moment you apply your 12v, it's going to switch on regardless of how good your the supply is on the trigger circuit (ie. load conditions of the car/supply).

Just a shame that getting a DPDT version is next to impossible unless you make something up (as a NC contact creates some interesting issues as it always has to have power) and the SPST ones aren't exactly cost efficient. This would mean that you essentially loose your fail-safe since when there is absolutely no power, the speed sensors are disconnected.

Edit: Oh damn. I wasn't thinking 100% clearly. I have never really dealt with SSR's at low voltage/current load levels. I just realised one big problem with using a SSR for our circuit above.

Because a SSR load side is isolated from the control side, the load side requires at least some minimum voltage to function as the semiconductors in there will not operate with no load. So basically, if your speed is too low that you aren't getting the minimum voltage output from the speed sensor, the SSR will not complete the circuit on the load side despite the control side having power applied. This explains the issue you are having Steven, though it's not due to the control side having a lower voltage, but rather because the wheels aren't moving.

[Steven]

Only my button circuit is solid state (kinda) my switching circuit uses good ol reliable relays

[Steven]

Btw what i meant with the ssr's was the circuit also flowing in the opposite direction at times (for a dc signal current must go both ways)

[fuel miser]

Here is a little info on the speed of the switching of SSR's.

Get the one that can handle the current required. Reason is if you buy say a 5A SSR you will need to pass maybe 10mA or greater (check the datasheet for minimum current required to achieve the quoted switching speed).

It sounds like you are passing bugger all current and relying on the voltage level to be passed to the computer.

It should also be noted that you cannot use a AC SSR to control DC. IGBT SSR's can switch AC & DC thou, you are not likely to buy these at Jaycar, ***** Smith to cheaply. They are used in variable speed drives.

Good quality DC SSR will have MOSFET's not transistors, this enables high switching speeds.

See the specs below for typical MOSFET SSR's below.

Input

Min turn-on voltage/current 4 VDC / 10 mA

Max turn-on voltage/current 32 VDC / 20 mA

Min turn-off voltage 1 VDC

Output

Max on-state voltage drop at current output at 40ºC base plate temperature 1.5 - 2.2 VDC

Leakage at 50°C 1 - 2mA

Max turn-on output time, control input at >8VDC, DC Line at >8VDC 25 µsecond

Max turn-off output time 25 µsecond

Hope this helps, I built a DC SSR high speed gluing speed that could operate at 600Hz for placing droplets of glue along the side of multi part forms.

To get to this speed I had to ensure that I always drew slightly more than the minimum ON current, by placing a resistor in parallel with the load.

Unfortunately this will not help you as you are looking at the voltage level not sourcing or sinking current.

Edited January 30, 2011 by fuel miser

[DJKOR]

Only my button circuit is solid state (kinda) my switching circuit uses good ol reliable relays

Okay then, that can possibly work for the initial plan since you are only using it for the activating and deactivating of a separate circuit. However, does your switching relay have a built in resistor? If not, I would parallel a resistor with it. Reason for this is that SSR's can do some funny things with an inductive circuit. What will happen when you switch it with the SSR is that it will firstly activate the relay because the initial current required to switch the relay will be at it's greatest, but once the relay is turn on, the current required to keep the relay on is reduced. When the SSR switches off, the leakage current through the load side of it may possibly be just enough to keep the switching relay on. Just something to consider.

Btw what i meant with the ssr's was the circuit also flowing in the opposite direction at times (for a dc signal current must go both ways)

You can get AC SSR's which are designed to overcome issues like that. However, as far as I'm aware, the issue is not with regards to allowing the speed sensor output to flow though it (since once the SSR is active, current can flow both ways though it.. don't quote me on that though), but it's more for when the SSR is off. A DC SSR in the off state will potentially allow half of the AC cycle to pass through it.

Hmmm. Maybe the good old fashion relays are perfect for this job. Was pretty cost efficient as well I must add. All I've used are 3 relays, 2 D15 connectors, a switch, and some wiring.

[fuel miser]

If you are using SSR's to switch inductive loads (coils of relays etc) then you need to use a diode across the inductive load.

DC on AC SSR (as they use an SCR or TRIAC) will not work reliably as they are designed to handle sine wave where you control the switching circuit on both sides of the sine wave. You would need IGBT SSR's

Chances are that on DC it will turn ON and not turn off.

Edited January 30, 2011 by fuel miser

[Steven]

I think i have caused some confusion. My switcher is a transistor running off an ic chip, which in turn runs a 6v relay (with a diode connected in parallel) which in turn runs the switching relays

[Steven]

Now I'm back home at the computer I have a better grasp of what's being said here and obviously I'm in the company of some fairly experienced technicians.

One of the main reasons I'm using a 6v relay is because somehow, despite having a regulated 12v input to my IC, I'm only getting around around 6ish volts at the output of the transistor when the IC is outputting a high signal yet the main concern is that in the low state the IC is still feeding the transistor around 2volts!

With a 12v relay I simply wasn't getting the required power to switch them on, with a 6volt relay the current is sometimes too high to let it switch off (and if I add more load to the the relay to drop the overall voltage, there isn't enough juice left to turn the relay on in the high state).

my "button" IC circuit is attached. The relay in the picture is the 6volt I'm currently using. At the moment I've sort of gotten around this but connecting a zener diode in series with the relay (just normal bias as I ran out of regular diodes) and a 0.1uF capacitor in parallel with the diode. I found that only by adding the capacitor to the diode would the current be so that the relay would turn on and off (lucky guess?). The circuit appears to work in this manner but due to varying voltages in the car I'm concerned that when the car is running (and hence main power is higher, despite being regulated) the relay may be getting too much juice to switch off through the transistor (as the 2 volts in the low state is directly tied to the voltage level of the main input).

I have 2 ideas on how to fix this but no idea how to accomplish them. 1 is to make a "minimum voltage" at the relay in that if the transistor output isn't over at least 3.5 volts then no power gets through to the relay (so that way power only ever reaches it in the high state when output is at least 6 volts)

OR

figure out why the hell my IC isn't outputting only 0volts in the low state and make it so it does (circuit diagram attached. Experts please peruse and advise).

[Steven]

Well it looks like the circuit still works regardless, due to the zener diode/cap addition the relay sees 0.5v in the low state (easily switches off) and around 3.8v in the high state, which is only just enough to activate it (most likely will be higher though when the engine is actually running).

[DJKOR]

Now it's time for the longevity test. I wish I opted for an electronic circuit because that way I could use a proper button like you. Laziness got to me though unfortunately.

So... time now to build that interceptor connector I discussed with you earlier and to sell it as a mod

[trentmeyer23]

Now it's time for the longevity test. I wish I opted for an electronic circuit because that way I could use a proper button like you. Laziness got to me though unfortunately.

So... time now to build that interceptor connector I discussed with you earlier and to sell it as a mod

You two should really make this as a kit and sell it, and include the TC button...DO IT!!!

[DJKOR]

You two should really make this as a kit and sell it, and include the TC button...DO IT!!!

I've got an idea that can make it plug and play, but the bits I need would most likely have to be sourced to some factory in China. If I could, it could make one really neat solution.

Steven: I decided to take your idea and mount an LED indicator on the dash. I had a neat thought, but as expected, Toyota use ground switching for the dash indicator LED's. I picked up a couple of tri-colour LED's (red/green/orange) and the idea was to have it go green when the TC override is enabled and if for any reason the dash needs to give a warning light there, the red component of the LED would light up as well, effectively giving the orange colour. This way I can see if there is a warning light should it occur. But due to the common cathode of the LED, it makes it impossible to work it this way.

[DJKOR]

Okay, the last part of my TC switch is finished. In my opinion, the illumination of the button just wasn't enough of an indication to let you known that traction control is disabled. Following the suggestions from Steven to mount an additional LED in the cluster instead of utilising the existing one, I mounted a green LED in behind the traction control indicator position as well as the ABS indicator position just as a reminder. I was going to opt for an orange LED to keep it looking factory, but I settled for green in the end just to add a little bit of distinction between the two

And that now marks the completion of that project.

Just a quick video for reference which also shows the fail-safe automatic turn-on:

Total modification cost: $64.05. Total time spent: Way too much. Easily more than a few hours. That was with a lot of mucking around though.

Can be done more cost efficiently if different components are used or sourced alternatively. Most expensive component in this one for me was the switch which was $14.50. I obtained everything I needed from Jaycar, so that also explains the cost, but at least you can see that the parts are easy to obtain.

Edit: You know what I just thought of that would make you so furious that all you could do is laugh? What if all you needed to do to turn off traction control is short out two pins on the Skid Control ECU or ground one of them?

[Steven]

I tried an alternate electronic switching circuit that revolves around a 555 timer rather than the currently used 4013 IC, as the 555 timer required far fewer components and was more compact overall. I checked my circuit several times over but in the end it appears the circuit design I followed is flawed and does not work. So I'm stuck with my current design which means the switch won't work if the battery is low (which is a moot point because when the engine is on and the alternator charging the battery is always plenty high enough. I'm talking sub 12volts before issues arise.)

Also just realised this but technically wouldn't the Aurion be unable to drive a dyno without the traction control disabled?

[DJKOR]

I tried an alternate electronic switching circuit that revolves around a 555 timer rather than the currently used 4013 IC, as the 555 timer required far fewer components and was more compact overall. I checked my circuit several times over but in the end it appears the circuit design I followed is flawed and does not work. So I'm stuck with my current design which means the switch won't work if the battery is low (which is a moot point because when the engine is on and the alternator charging the battery is always plenty high enough. I'm talking sub 12volts before issues arise.)

That's a bit of a bugger about the 555 circuit. Probably better than my skill though. When I tend to build a circuit from plans, it never works like it should.

Also just realised this but technically wouldn't the Aurion be unable to drive a dyno without the traction control disabled?

Correct. But I think if you run your Aurion on the dyno, you should still disable the TC via the traditional method. Why? How the heck can the dyno operator check your RPM speed?

[Steven]

I tried an alternate electronic switching circuit that revolves around a 555 timer rather than the currently used 4013 IC, as the 555 timer required far fewer components and was more compact overall. I checked my circuit several times over but in the end it appears the circuit design I followed is flawed and does not work. So I'm stuck with my current design which means the switch won't work if the battery is low (which is a moot point because when the engine is on and the alternator charging the battery is always plenty high enough. I'm talking sub 12volts before issues arise.)

That's a bit of a bugger about the 555 circuit. Probably better than my skill though. When I tend to build a circuit from plans, it never works like it should.

Also just realised this but technically wouldn't the Aurion be unable to drive a dyno without the traction control disabled?

Correct. But I think if you run your Aurion on the dyno, you should still disable the TC via the traditional method. Why? How the heck can the dyno operator check your RPM?

Don't you mean speed? The rev counter should be fine I would have thought.

I'm still having trouble with this damn thing, now I'm getting 3.5v - 11vs through the transistors but that's changing to around 2.8v - 5.5v under load (when the relay is connected). 2.8v is still enough to switch the 6v relay. This has only happened since I have tested the unit with the engine running so with the battery at maximum voltage.

Going to try a few more things tomorrow but damn this is annoying. Now I need to have enough buffer in the minimum state to ensure that under no circumstances with the Traction Control turn off without the button being pressed!

If I can get to Jaycar I'll put together a voltage comparator and place it between the IC and the Transistor. HOPEFULLY that will work