Kevin,

It was actually your experimentation with the square wave indicator that lead to the success of what I have done. I found this thread by Googling the Yaris ECU part number. According to what you found, 5 pulses per second got full assist, between 45 and 75 pulses per second gets medium assist, and over 75 pulses per second result in the least amount of assist. However, my Holley ECU outputs in pulses per mile. It seems to me that the break points for the three level of assist can't be changed. The Yaris ECU will respond to the pulses in the same way, based on its internal programming. However, the way I see it, I can fool it into triggering the middle level of assist at what MPH I want for my vehicle, by changing the PPM that the engine ECU outputs.

This is where my friends spreadsheet comes into play. Assuming the Yaris ECU is programmed to see a 4000ppm signal (this may well be true as this seems very common), then based on that output, the Yaris ECU would trigger middle assist at 40mph. This seems pretty reasonable. By me outputting 4629ppm, I am pretty certain this makes the Yaris ECU triggers the middle level of assist at 35mph. I think my logic is correct, but I am open to suggestions. I would also gladly share the spreadsheet that my buddy made. 

Andrew

Andrew

Please do not take the numbers I reported as "Cast In Stone"  as my test setup is not exactly Lab Quality
The pulse generator I was using could not be changed on the fly, you had too stop it then enter the new frequency and restart it.

I wish I had a generator that could sweep thru the rates so you could realty see how it changes, I have to assume it is not in 3 steps but is somewhat progressive.  Well you now have that generator, it's your Cougar.  I hope we will hear more from you about what you discover as you drive it some more.

We are still learning the ins and outs of this system, keep us posted  on anything you find

Kevin

The issue that I see happening is that I have no concrete to know what the Yaris ECU is actually doing. I can definitely sense a change in steering effort as speed increases, but as you all know, steering effort naturally gets easier as speed increases. One way I thought about testing would be to jack the rear end up and see what happens to steering effort as the car is standing still, but the ECU "thinks" it is moving. The other problem that would be good to solve is how to turn the Yaris ECU on before the car starts moving. This is really only a minor annoyance at the moment, but would be cool to fix.

I can create a PWM+ output on the Dominator. The PWM+ pulse sweeps from 0-5v. I think as long as it sweeps above and below .5v the Yaris ECU will interpret that as a speed signal. I can run that output to the same #6 pin where the VSS signal is and program it to come on as soon as the ECU is powered up and pulse for a given amount of time, say 5 seconds. This might work.

As always, input is appreciated.

Andrew

Hope you guys have good insurance when that system steers you over a cliff! LMAO!

"FREE SAMPLE"

Andrew said
"I can create a PWM+ output on the Dominator. The PWM+ pulse sweeps from 0-5v. I think as long as it sweeps above and below .5v the Yaris ECU will interpret that as a speed signal. I can run that output to the same #6 pin where the VSS signal is and program it to come on as soon as the ECU is powered up and pulse for a given amount of time, say 5 seconds. This might work."

 I do not see any reason why that would not work,
If I ever get to it I was thing about putting my flashing LED on a relay with the coil powered by the start terminal on the ignition switch, while cranking the LED would be connected and when running the VSS sender would be connected. As long as the crank time is long enough it should work. My other thought for relay drive was the Stator terminal on the alternator, I think it goes positive when the alternator starts charging

Kevin

If the vss will not generate the signal desired, you might be able to use something like an Arduino or Raspberry Pi and program it to monitor the signal and modify the output to the ecu.  It could also be programmed to produce pulses when powered on, or other conditions, which might help overcome other obstacles.  That way, the vss and even gear changes won't matter as you program it as required.


Lawrenceville, GA

Charlie, Thats a good Idea but when I retired I swore I would never program another device again LOL

But seriously the ability to provide power up pulses and  also modify the pulse count to make things happen at diffident speeds looks like a solution. Not that I want to make this any more complicated than it is, LordGaga already has us going over a cliff LOL

Thanks for the idea      Kevin

I am checking with some people at Holley to see if it would be a problem to run the PWM+ output wire to the same pin as the VSS input. I don't see why this would be a problem, but in case it is, I was thinking I can use diodes and effectively isolate those two outputs, while still feeding them to the Yaris ECU. The last thing I want to do is let the pixies out of my very expensive Dominator ECU! LOL

Andrew

Andrew

Would like to hear what Holley has to say about combining signals, the way you now have it programed are you using a negative going square or PWM wave?   IE: is the Holley ECM pulling the Yarus VSS input to ground?   That is how all my testing has been working, my Flashing LED connects to the VSS pin and ground so every time it flashes it is drawing current from the Yarus VSS pin effectively pulling it to ground.

Since the Holley ECU would only be providing a ground to the VSS pin I do not see any problem bridging 2 outputs together as long as they can never source a positive voltage it should work fine.

I looked at the ProTouring site you linked and it turns out I was following your Cougar build a while back and lost track of it when I lost my shortcuts in a crash. Love the car and the attention to detail  in the build. You really need to do something about the paint ( just kidding, I love the look)

Let us know how it works out                          Kevin

Kevin,

Thanks for the compliments! The Cougar has been a really fun build and I really do use it as a daily driver. It's in the mid 30s here today and I plan on going to the store shortly...

Here is what the Holley documentation says about the speedometer output signal (this is what I am using to feed the Yaris ECU):

"This creates a +12V square wave Output that can be used to trigger an electronic speedometer.
The "Speedo" Output must be Pin Mapped to an available "P+" or "P−" pin on Connector J1(B), J2(B) or J3.
I realize the Transmission ICF Speedometer Output is displayed as PWM+/− (depending on the Output Type
selected in the Inputs/Outputs screen), but the ECU outputs this as a +12V square wave "Speedo" signal.
This is a Pulses Per Mile output signal, not PWM+/−. Pin Map the Output & connect it to your speedometer."

I wish I knew more about electronics!

Andrew