Andrew

I have not found any other pin that will wake the unit up, Only way I have found is to pulse the VSS pin
What you found about needing the canbus RPM signal would need to be proven before I would believe it. I have proven there are 3 levels of assist and do not think it does any more.

On the wheel return issue, I do not have any issue with that, my wheel returns almost to center on it's own but it always did as I have more + caster then the spec calls for.   If you unplug the motor from the ECU does the wheel return any better?   You have to remember for the wheel to return the steering gear has to drive the worm gear on the motor   I always thought you could not drive a worm backwards, thats why they use them in winches.   Their is no way that the ECU can assist in wheel return as there is no way for it to know the steering gear is trying to return, the torque sensor is on the wrong side of the unit for that. The only way that the return can be hindered is if the ECU shorted the motor leads loading down the motors ability to generate reverse voltage, unplug the motor for a test.

There was something else but I do not remember what it was, I will in my sleep tonight and will reply LOL

Till Later               Kevin

Kevin,

I firmly believe in your bench testing and it has been invaluable!!! What concerns me is the failsafe chart from the Toyota FSM. See below:



See code U0105. What is not clear is if this code is set for a non-ABS steering ECU. This is another reason why I can to be able to establish communication with the steering ECU through a OBDII connector. With that connection established, I should be able to read code, clear codes, and do the torque sensor zero point calibration. This seems valuable for many reasons.

Andrew

Andrew

The next code down  U0121 ABS communications error leads me to believe that that chart is for a Yarus or Prius  with ABS. We are working with a NON ABS Yarus steering ECU

We have already proven there are 3 levels of assist where the chart state both codes will result in a fixed 43 mph assist level

Kevin

That picture is right out of the FSM for a 2007 Yaris. At various points in the manual it references both steering with the ABS and the non-ABS steering computers. 

I might be over thinking this, but I going to get all of the connections made between the steering ECU and the DLC3 connector. I am have also talked to a car buddy/computer geek, and he is going to make a Arduino powered CAN simulator. He has done this before and feels it is totally doable. The CAN simulator will act as the other terminator for the CAN network (in the Yaris FSM it is very clear that the engine ECM is one end of the CAN bus and the SP ECU is the other end). The CAN simulator will be programmed to send a constant RPM signal so that the steering ECU thinks the engine is running. 

Today I also happened to be walking out of the store when a Yaris pulls into the parking lot. I approached the driver and asked if he had power steering with the key ON and engine OFF. He wasn't sure, but we tested it, and sure enough, no power steering until the engine starts. 

The reason that I am going through all of this trouble is to make the steering ECU happy and not set codes. The reason we can't have codes is because if there are any codes, the ECU is not going to perform the torque sensor zero point calibration. I really want to perform this and see if the return to center improves. Also, as noted in the codes chart, if the steering ECU is throwing those codes, I do not believe that speed sensitive steering is active. 

Andrew

Andrew

I would not expect a Yarus to have power steering with just the key on. If it's Non ABS we know for sure that it needs VSS pulses and you are working on proving the CanBus RPM signal is needed.

Have you tried unplugging the motor from the ECU to test the return to center, If return to center is still slow unplugged I do not think anything you do will improve that. Remember, you are driving a worm gear with the steering shaft and while the out of the car tests indicate the EPAS shafts turn with very little resistance is this what is slowing the return ??

Kevin

I asked the kid that was driving the Yaris today and his does have ABS.

I have unplugged the motor before and taken a spin around the block. It was the worst possible scenario. Super high steering effort and a very...very poor return to center. Way worse than with the motor plugged in. 

I will think about all of this some more as I travel tomorrow and enjoy some turkey on Thursday. I hope everyone has a great Thanksgiving holiday!!!

Andrew

Andrew

Ok,so the Yarus has ABS so the only way it could turn on is VIA CanBus and we assume it gets an RPM and when moving VSS so I guess it is expected that it would not turn on with just ignition.

The motor unplugged is kind of unexpected, I was not aware that the ECU provided any power to the motor on return. I will try to play with that a little over the holiday but it will be with a Prius ECU. Just to confirm, you had the motor unplugged from the ECU, not the power to the ECU? Please confirm this for me

Enjoy your Thanksgiving, we will be at home so if I need an escape I may find time to play a little.

Kevin

Andrew

I did find the Yarus ECU and found the following

For these tests a Prius steering motor and gear box were strapped down to the workbench with 8" Vicegrips on the input and output shafts.

With the ECU enabled via VSS pulses turning the output shaft (as it would be on wheel return) is met with very slight resistance, slightly restraining the input shaft (like a tight upper column bearing would do) greatly increases  the resistance as the torque sensor is trying to counter the the input.
On powering down the ECU, the same very slight resistance is still felt.  If you unplug the motor from the ECU most of the resistance goes away, only the rotating resistance of the gears and motor remains.
Putting an ammeter in series with the motor and the ECU shows about 500MA of current when the output shaft is rotated and the motor becomes a generator
Putting a dead short on the motor leads makes it very hard to rotate the output shaft.

My conclusion is that the ECU presents a slight electrical load to the motor when it is is being driven by the output shaft and is generating reverse current but I do not feel this very slight restance inhibts steering return very much if at all.  
What I to find will inhibit return is a tight upper column bearing as the torque sensor picks this up as steering wheel input counter to the direction of shaft rotation bringing on assist to counter it.
If you has the entire original column to work with remember the top bearing, it was a very good quality shielded ball bearing, I wonder if that's why.  Thinking further, the Mustang has 2 horn brushes where the Yarus has a clock spring , I Assume the Cougar is the same as the mustang. Could the brushes plus a slightly binding upper bearing cause this??

You still have to tell me what happens when you unplug the motor leads from the ECU, does the wheel return get better??

Let me know your thoughts                   Kevin

Kevin,

I did drive without power to the motor and the return to center is even worse than with power applied. 
The Cougar turn signal switch is exactly the same as the Mustang, so there are two horn contact brushes. I just installed a new turn signal switch and I can't imagine that the horn contact brushes are the cause. 

What might be happening is that the way I have the upper column tube being attached to the Toyota motor is causing some bind in the upper shaft. I am going to revisit this further in the future. The collar that I welded to the upper tube only has one set screw, so when that set screw is tightened, I think this puts some bind on the upper shaft. I think a way to solve this is to install two more set screws (so 3 set screws are 120 degrees apart) and tighten them evenly to keep the upper tube square and concentric with the Toyota motor. 

Andrew

I see on the other site that you have some projects going with CanBus, let us know if and how it works out

I am still puzzled by the poor return with the motor unplugged as it is opposite what I find on the bench.
Just to be sure You have the motor unplugged from the ECU and not the ECU unplugged from the power connector, correct

Hope to hear of some progress                  Kevin