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Discussion Starter #41
Today I was able to do some testing. I didn't want to wire everything up permanently only to have to chase things down later. So today I simply wanted to see if Blake's box works. The definition of "works" is, will the steering ECU turn on when it sees an RPM signal over CAN. I wanted to do more, but I didn't have enough terminals for the little connector that plugs into the steering ECU. There is a Prius at a junk yard not to far from me. I plan to take a trip and see what I can rob off it.

I connected the CANHi and CANLo at the steering ECU (on the D31 connector) to the CANHi and CANLo on Blake's box, making sure to twist the wires. I installed the wires into the Molex connectors for power and ground, ran the ground under the dash and had the power wire ready to connect to a temporary power source.

I turned the ignition ON, and as expected, there was no power assist. As soon as I applied power to Blake's box, almost instant assist. Blake said that his box should come online in less than a second, and that's about right.

I then went for a drive, not really expecting any difference, but to my surprise, there was a difference. At low speed there is considerably more assist and as speed increases there is a noticeable drop in assist. So contrary to my previous proclamations, and counter to the results that some people have done with bench testing, I don't believe that the speed sensitive steering is active if there is no CAN signal. This makes sense, because in the Yaris FSM it clearly states that if there is a CAN communication error with the engine ECM, it defaults into "failsafe" mode (fixed assist at the middle level). The RTC was about the same, but I expect this to improve once I get the OBDII connector wired up, scan and clear any codes, and perform the torque sensor zero point calibration.

Progress is being made.

Andrew
 

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Discussion Starter #42
Just a tiny little update. The weather has been cold and rainy, so no work is being done, but I did receive some parts. I like doing a proper wiring job and that means not doing any butt connections with the wires if it can possibly be avoided. This means spending some time looking at catalogs and data sheets for the right terminals.

With the Yaris (and Prius) steering ECUs the wiring that needs to happen is on the D31 connector. This is where the +12v power pin is located, along with the speed signal, CANHi and CANLo, etc....I have a D31 connector that I clipped from the donor car so what I needed were the actual terminals to avoid butt splicing wires and to add pins as needed. I was also looking to find the connector itself, but had no luck, but the Toyota dealership has them for $6. However, the dealership does not have and can't even look up the terminals. As far as I could tell the connector is made by TE Connectivity and the stock terminals had Tyco stamped on it. A little time spent in the TE Connectivity catalog resulted in a reward.

I know this may seem like overkill for most people, but if I am going to all this trouble, I might as well take it 100% of the way.





Once I get a dry sunny day, I can wire up the rest of the wires for the OBD2 connector and see if I can read fault code using the Blue Driver OBD2 dongle and android app.

Andrew
 

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Discussion Starter #43
I just posted a new video to my YouTube channel. The video is to demonstrate what it is like driving a dog-ring T56 around town, however, you can clearly see the steering wheel and how it moves around during turns. Hopefully this will give a basic idea of how it is working for me.


If you find this content useful or entertaining, please consider subscribing to my channel.

Andrew
 

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Hey Andrew, I've been following your thread for a while, I've also been following a tilt steering out of a late 80 f series truck and decided I want the best of both worlds. I have been working on the tilt in combo with the prius epas that you wrote up on, it is a lot of work, and a bit of research. I am almost done if not for the long shopping, and machine shops being closed. If anyone is interested I can add a little write up for tilt in the prius colum. It cost me about 250 for both including coupling, and fab.
 

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Discussion Starter #45
Hey Andrew, I've been following your thread for a while, I've also been following a tilt steering out of a late 80 f series truck and decided I want the best of both worlds. I have been working on the tilt in combo with the prius epas that you wrote up on, it is a lot of work, and a bit of research. I am almost done if not for the long shopping, and machine shops being closed. If anyone is interested I can add a little write up for tilt in the prius colum. It cost me about 250 for both including coupling, and fab.
I am sure people would be interested in seeing what you have done. Please post pictures, etc..., here or start your own thread. I know I would be interested in seeing!

Andrew
 

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Yes, start a new thread on this conversion. It would be very interesting to see how this was done.



Hey Andrew, I've been following your thread for a while, I've also been following a tilt steering out of a late 80 f series truck and decided I want the best of both worlds. I have been working on the tilt in combo with the prius epas that you wrote up on, it is a lot of work, and a bit of research. I am almost done if not for the long shopping, and machine shops being closed. If anyone is interested I can add a little write up for tilt in the prius colum. It cost me about 250 for both including coupling, and fab.
 

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Discussion Starter #47
Sometime in December, I was chatting with my friend John, and we decided that my wife and I would visit him and his wife for New Years. John and I met around 2003 when I was at the Bristol Bash competing in the Car Craft Eliminator competition with my 1970 GTO. John is a super smart guy and a great fabricator. He built an amazing 1967 Nova some time ago and has since built a few cars for clients, but his day job is being a computer geek. Here is his Nova (it has traded hands several times since he built it):



Anyway....LOL...John has a great shop and we decided that while our wive's do whatever it is they want to do, we would hang out in the garage and improve on the EPAS installation in my Cougar. As you may recall from my original post, I had turned down a 1.5" ID steel collar to fit inside the bottom of the upper tube. This allowed for a method of attaching the upper tube to the Prius motor. While I think was was a decent solution, I couldn't help but think that having only one set screw holding the upper tube to the motor was inadequate.

John has a little lathe, so we turned down another steel collar, so it would slip inside the upper column tube.



This collar was positioned a few inches up from the bottom collar and was welded in place through holes that we drilled through the tube.



The last thing that we did was add two more holes to each collar, so that each collar now has a total of 3 set screws that are located 120 degrees apart.



I felt that doing all this would keep the upper tube more firmly attached and square to the Prius motor.

I don't know that doing all this made any tangible difference in the way that the system functions, but if anyone is doing this from scratch, I think this is a good way to go.

As always, questions and comments are welcome. I also want to thank those of you that have subscribed to my YouTube channel. I really appreciate it!!!

Andrew
 

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Discussion Starter #48
Not much to report in terms of progress or any other updates, however, I finally managed to track down the Yazaki part numbers for the big power connector for the steering ECU. The same connector is used on both the Prius and the Yaris steering ECUs (and probably others of the same vintage).

The connector housing body is 7283-3521-40





The terminals are either 7116-3097-02 or 7116-3098-02 (either will probably work).





The big challenge is sourcing the terminals in the US. The connector body can be purchased from Toyota under PN 90980-12653, however, Toyota does not sell the terminals.

I was actually able to source the connector housing bodies from Japan, but what I originally thought were the correct terminals, ended up being the wrong ones.

If anyone knows a source for Yazaki parts in the US, please let me know.

Andrew
 

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Discussion Starter #49
Yes, I know, at the end of the day, if you have a pigtail that came with the donor steering ECU, you can solder or use a quality butt splice, and be done with it. However, for those that want to do this in the most optimal manner, this information will be quite valuable.

So here is just another tidbit of information, just in case anyone else wants to go down this rabbit hole. I found a vendor in Japan that has the connector housing body, but again, these can probably (I have not tried ordering myself) be sourced from your local Toyota dealership. I did successfully order the connector housing from the Japanese vendor.

Here is the connector body:
https://global.rakuten.com/en/store/auc-hi-1000/item/2p375-a-yz-f-tr/?l-id=rgm_item_en_rvp_widget

They also list the matching terminals. Yes, they fit the connector, but as you can see from the picture, they are not designed for 8-10 gauge (5-8mm2) wire. They are designed for 3mm2 (12 gauge) wire.
https://item.rakuten.co.jp/auc-hi-1000/f375-yz-s/

I suspect that the terminal above is Yazaki PN 7116-3096-02 (too small).

I have tried asking the vendor if the correct terminal is available, but as of yet, they have been unresponsive. The language barrier and the time difference is making communication problematic.

Andrew
 

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Stupid question...but have you tried Digikey, Allied, or Mouser Electronics? It's been a few years since I have used them but I know I used to always found odd tidbits from them. I know they carried a lot of Tyco products, but also had other manufacturers.
 

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Discussion Starter #51
Stupid question...but have you tried Digikey, Allied, or Mouser Electronics? It's been a few years since I have used them but I know I used to always found odd tidbits from them. I know they carried a lot of Tyco products, but also had other manufacturers.
Not a stupid question at all. I've purchase all kinds of things from Mouser, DigiKey, and Waytek Wire. All great companies to deal with. The problem is that Yazaki only has one Western hemisphere distributor. I was in touch with them this morning, and while the sales rep was sympathetic (a Ford guy) he wasn't able to help. They haven't stocked that particular part number in years and if he was to order it, I would have to buy a spool (1200 pieces). That's a no-go.

I don't mind ordering parts from Japan, the shipping was rather reasonable (all things considered), but the vendor I purchased from before, has been ignoring my follow up emails. :shrug:

Andrew
 

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Discussion Starter #52
I recently completed a 1000 mile road trip in the Cougar and I noticed that the steering was particularly numb on center. While driving down the highway I found myself having to constantly steer it in order to keep it going straight. I attributed this mostly to the windy conditions that I encountered at various points on the trip, but I didn't give it much more thought.

After getting home, I noticed that there was a little squeaking noise from the front end when I made slow right hand turns. I suspected that maybe the preload on the front bearings has loosened up, so I jacked it up to investigate. Rocking the wheel at the 12 and 6 o'clock position really didn't show any unusual looseness in the bearings, however, I did find significant slop when I rocked the wheel at the 3 and 9 o'clock positions:


Although all of my front end components are "new" they do have about 15K miles on them since installation. After seeing the slop in the rack, I called TCP and was surprised and pleased to get a live tech guy on the line. His name was Mike and he was very helpful. He told me that due to the straight cut gears of the rack and pinion gears, periodic inspection and adjustment is necessary to minimize the backlash. He outlined the procedure and I went outside and did it. I also noticed that the passenger side inner tie rod was a little loose where it was bolted to the rack, and I was able to address that.

Needles to say, the steering feels much better. The return to center is much improved and the on center feel is also much better (no duh...considering how much slop was there)! I plan to have the car up on a rack in the near future to inspect all of the steering and the suspension components and fix anything I find.

Take away: don't assume everything is tight and working properly just because all of the components are "new."

Andrew
 

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Discussion Starter #54
Overdue update. I have been driving the Cougar a lot and am mostly happy with the EPAS. I recently fine tuned the adjustment on the TCP rack again and once it was set right, the steering is better than ever before, but still not as good as I want.

It might be that I just have expectations that are too high.

Andrew
 

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Andrew, Any updates on the Prius steering? I have installed one in a torino and have to constantly correct it going straight down the road. Did any of your mods improve RTC? Also is failsafe mode for Prius at the highest assist level or once you hook up VSS and controller it is higher? Thanks
 

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Discussion Starter #56
Andrew, Any updates on the Prius steering? I have installed one in a torino and have to constantly correct it going straight down the road. Did any of your mods improve RTC? Also is failsafe mode for Prius at the highest assist level or once you hook up VSS and controller it is higher? Thanks
Sorry for the delay in responding. I have been traveling this week and just got home. For me the biggest improvement in RTC was getting the backlash adjusted properly in my TCP rack. There is a speed spot between having too much slop and the rack being too tight.

The Prius ECU (which I am not using) does have power assist after about 5 seconds of being powered up. I am not sure if this is exactly what you were asking. The non-ABS Yaris ECU does vary the level of assist, when provided with the proper speed signal. I do this through the Holley Dominator ECU. From what I understand, the Prius ECU in fail-safe mode provides the "middle" level of assist (the Yaris has 3 levels of assist based on speed).

Andrew
 

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Ok,so there may be more assist with the Prius unit when not in failsafe? I wonder if that would help RTC? Were you able to ever perform a zero point torque sensor calibration? Did it help? I really don't care about RTC as much as the constant corrections needed when going straight down the road. Thanks
 

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Discussion Starter #58
Ok,so there may be more assist with the Prius unit when not in failsafe? I wonder if that would help RTC? Were you able to ever perform a zero point torque sensor calibration? Did it help? I really don't care about RTC as much as the constant corrections needed when going straight down the road. Thanks
As I understand it, the Prius failsafe mode puts the assist at the medium level, while the Yaris non-ABS ECU provides 3 levels of assist, provided you have the proper speed signal going to it.

I was not able to to perform a zero point calibration. I got discouraged by this because I don't have easy access to the Toyota specific scan tool that is needed.

The return to center is pretty good, until the last 10-15 degrees around "straight." This is left/right 10-15 degrees range is the source of much of my dissatisfaction with the whole upgrade, but to be honest, I think most people would be OK with this. I have nearly 5000 miles on the car since the EPAS install, and I don't dislike it enough to take it off. In other words, I think the driving experience is better with the EPAS than without.

If I was to do this again, or for anyone that really cares to do the best job possible, I have some recommendations. For the EPAS to function optimally and for the on center feel to be as best as it can be, the mechanical installation process should be executed very precisely. Here is a list of things that I would consider doing:

1. Instead of using an existing column tube, I would start with schedule 10 pipe that is of the same O.D. as a stock column tube. The reason for this is that the pipe is much stiffer and there is material to machine, as needed.

2. I would not cut the tube with a saw or cutoff wheel, but have the tube machined on a lathe to make sure that the ends are square and true to the tube.

3. I would make sure that the upper and lower shafts are very straight. I would say no more than .010" runout. If the shafts are not straight, it introduces bind into the EPAS unit, which in turn reduces good RTC and on center feel.

4. Make sure the ECU gets good clean power and is grounded well. My power leads come off a big OEM style power distribution module that gets power directly from the battery and the motor ground wire is the same gauge as the power wire and connects directly to the engine block.

I hope this helps.

Andrew
 

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Awesome write up. Thank you for that. I agree the last 10 15 degrees is the killer here,having to "steer" the car when going straight. I did build my first setup on a lathe and on mill so I know it is all straight with no binding but it still has this problem.
So if I read everything correctly, I can use my Prius motor with a non ABS Yaris ECU.Then use a Dakota Digital GPS interface along with my VSS. That way I get the 3 assist modes depending on speed. Would it then be adjustable because I would like full assist all the time,thinking it would help RTC. Thanks for all the info.
 

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Discussion Starter #60
Awesome write up. Thank you for that. I agree the last 10 15 degrees is the killer here,having to "steer" the car when going straight. I did build my first setup on a lathe and on mill so I know it is all straight with no binding but it still has this problem.
So if I read everything correctly, I can use my Prius motor with a non ABS Yaris ECU.Then use a Dakota Digital GPS interface along with my VSS. That way I get the 3 assist modes depending on speed. Would it then be adjustable because I would like full assist all the time,thinking it would help RTC. Thanks for all the info.
I honestly don't "steer" the car very much to keep it going straight. I can definitely feel just a little bind in the steering wheel, but I am not constantly moving the wheel much. Also keep in mind that I have a TCP rack, which is extremely "fast" so a little movement of the steering wheel is noticeable.

Yes, you can use the Prius column with the Yaris non-ABS ECU.

The rest I can only speculate about, because I have not used any of the Dakota Digital boxes for this application. You'll be in uncharted territory. As for keeping the motor in high assist mode all the time, you will have to play around with the number of pulses that you send to the Yaris ECU. If I remember right (and I may have mentioned this earlier in the thread) the Yaris ECU goes from high assist to middle assist at 43 pulses per second. If you're able to set the pulse frequency that the Yaris ECU sees under that threshold (at highways speeds), then it will stay at the high level of assist.

Again, I am not speaking from direct experience with respect to the DD interfaces, only from I have been able to do with the Holley Dominator ECU.

Andrew
 
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