Hello Kevin

My name is Waid.  I was the guy that originally posted the Saturn Electric Steer when I discovered the guy in Europe and posted the $100 Electric Steering topics.

I am curious about the Yaris Electric Steer.  It appears that you not using the module from the guy on internet.

When say ECU, are you talking about the electric steering controller or the car computer ?

How did you wire it?  

http://www.fordmuscleforums.com/all-ford-techboard/538585-100-power-steering-yes-you-can-use-column-electric-power-assist-system-epas.html

http://www.fordmuscleforums.com/all-ford-techboard/538585-100-power-steering-yes-you-can-use-column-electric-power-assist-system-epas.html

By ECU I am referring to the Yarus steering control module from a non ABS brake equipped 2007-2009 Yarus, it has to be non ABS as it relies only on the Vehicle speed sensor (VSS) and does not use CanBus so no internet controller is required.

Wiring is simple,   Direct 12V from battery (about 50 amps max only when providing assist)
                             Switched  12V ignition to turn the unit on and off (less than 1/2 amp)
                             A pulsed to ground VSS signal to turn the unit on and control the level of assist

I still have not  installed a VSS and am using a flashing LED (the fake alarm indicator kind) to provide the 5 PPS to turn it on

I still want to install the speedometer driven VSS I have but have not have the time, without the VSS varying the assist it feels just like the original 56 power steering, very light and over boosted. It would be nice to reduce the boost at high speed and I will get around to it some day

So far I like it and due to some recent health problems it enables me to drive and enjoy the car instead of looking at parked in the garage.

Since the high current draw only occurs  when providing high levels of assist no upgrade to the charging system is required. going straight and in minor corrections at speed it draws nothing.

 
  

Kevin,

What is the part number on the Yaris Non-ABS ECU ?

Thanks

I have tested both these Yaris ECU's and they work fine. I also found a Prius ECU that will turn on after 10 seconds if it has no communication from the vehicle ECU. Guess this is a fail safe to allow power steering when the vehicle is being pushed or coasting to the side of the road if the engine dies.

ECU 89650-350    08 Yaris* Works in VSS Pulse
Jtekt     991-39900
112900-2200
EPS 12V Denso
Toyota parts zone says 07-09 yaris  89650-360 is the replacement for this unit
OEM Parter  says 89650-360 is the replacement for this unit
 
 ECU 89650-140    08 Yaris* Works in VSS Pulse
Favess  991-28701
112900-1062
EPS 12V Denso
Toyota parts zone says 07-09 yaris this is a current part #
OEM Parter says this is a current part #
 

A square wave generator is easy. I built one to run my electronic speedometer in my streetrod. I used a g.m. Speed sensor from a 90s 4l60e transmission. I then made an aluminum disc about 5 inches in diameter and mounted a number of disc magnets in it. I then bored it to fit on the driveshaft and presto a square wave generator!

Mike, still lovin his 57 t'bird after 53 years!

I already have a VSS that I can splice into the speedometer cable (may need an adapter on 1 side).  I have already run the VSS with a cordless drill and it will do what I need.   Just need to get my sore butt under the dash to get it done, looks like a winter project 

Kevin,

I have the wiring diagram for the Prius and also the Yaris both Prius and Yaris are connected to the can bus.

Yaris steering ECU uses the VSS signal which is fed by the speedometer for variable power assist.

Prius does not have a VSS signal input. Per the manual it will default to a preset power assist if the can bus is not connected. As you stated earlier the Prius electric steer will work after about 10 second delay because it is trying to communicate with the can bus.

I have bench tested the Prius EPS on default fail safe mode but not sure how much the power assist is until I put wheels on car and test it.

My question to you is since your Yaris steering ECU is also not connected to the can bus do you get instant power assist soon as you turn the ignition on or do you also have to wait about 10 seconds?

Waid

Waid

The 2 Yarus ECU's I have tested will not provide any assist at all without can buss till the VSS input sees about 5 pulses at around a 5 PPS rate. I provide this pulse train using a flashing LED (the kind you buy to make it look like your car has an alarm system)    The LED is wired Positive to the VSS pin and Negtive to Ground. Every time it blinks it pulls the VSS pin to ground, fooling the ECU VSS into sensing that the car is moving.

You are correct that the Prius ECU will turn on in a few seconds without can buss but it will always be at full power assist as it has no VSS input (the pin is there but has no voltage on it like the Yarus does.  With the Yarus I can put a VSS driven by the speedometer and have variable assist, I intend to do that this winter.

At full assist the steering feels overboosted, not unlike the factory hydraulic system.  I had a friend who has the factory system in his car drive mine and he did not feel any difference

I got my hands on 07 Yaris steering column with ECU non-ABS ($36 ! ).  I already had a pulse generator with flashing LED with variable duty cycle and I was able to actuate the ECU.  The Yaris EPS is much smaller compared to Prius which is fine if you are using manual steering box.  I used to be a steering engineer at Ford and I can tell you that the load rating for Yaris would be too small to be used with Rack & Pinion in a bigger car.  I have converted a Cavalier Rack to manual for my Falcon.  The good news is that the ECU for Yaris works with Prius EPS because both uses same torque sensor.  The Yaris ECU works instantly as soon as it sees couple of pulses even if the pulse generator is removed afterwards.  

According the Prius EPS troubleshooting guide, if the steering ECU sees CAN bus malfunction (like broken communication), Amount of power assist is fixed for a speed of 43 mph (70 km/h).   I assume this means that what ever assist level that is provided when everything is working fine at 43 mph.  Typically at 43 mph, there would be very little assist needed.  Therefore, I am thinking that the steering assist will be very low when the car is not moving.

I did an un-scientific bench test with Yaris ECU (with flashing LED) and Prius ECU.  I held the motor down by hand with the output shaft locked in vice with another person moving the input shaft with a vice grip pliers.  Both the Yaris and Prius did not feel any different in terms of how much force I had to apply to hold the motor down.  

I hope to test the entire system this weekend with both Yaris and Prius ECU.

You are correct, the Prius unit has a larger gear case than the Yarus but they both have the same motors.

I did testing with both types a spring scale to see how much power they can output, I used the Yarus ECU for both tests and the output for both was almost the same. It may be that the ECU is what limits the power.

I will say that the Yarus motor and ECU will dry steer my 56 Fairlane with radials on dry concrete and that's plenty for me.

The testing I did with the Prius ECU felt like full power without can buss where your research says it is at the 43 MPH rate, wish I had time to play with it some more but not now, may try more mid winter.

Keep us informed of any thing else you find, we all learn from each other. I never would have thought of this if not for the Mustang forums and their GM steering projects