Toyota FRS Electric Power Steering in an A Body

[jetmech442]

Objective:
Integrate a 2014 toyota FRS Electric Power Steering(EPS) system into my ’69 Cutlass, allowing the steering ECU to vary assist levels based on vehicle speed, mph, torque input and steering angle.
Motivation:
This car has always been more of a journey-not-destination thing for me. And as such I'm at the point where the Grand Jeep Cherokee steering box and stock LQ9 pump with Turn One reducer valve just isn't doing it for me anymore. I'd love to give Turn one or Lee a thousand dollars, but I don't have that kind of money, plus getting the known easy solution isn't my thing for some reason, I guess I just like the challenge of integration. I've got a build thread over on LS1tech https://ls1tech.com/forums/conversio...version-2.html where I started, if anyone is interested.
I’ll state here that I am not a CANBUS expert, I’m merely a novice with an Arduino and CANshield that is pulling data from multiple sources and doing his best to put the pieces of the puzzle together. I love discussion and feedback and always am eager to learn from the awesome people here at protouring and my goal is to help others on their path.

So this project, as most of mine do, stands on the shoulders of giants. Below is where the majority of my knowledge came from-people freely sharing what they've learned for the love of cars. Hopefully someone someday will use this to do something even cooler(also kind of assuming that this project is successful in the end, lol). I'm a thermal engineer by day, which means I know lots about temperature and not lots about CANBUS or electronics. I dabble in Arduino, but most of what I do with it is based re-purposing other peoples code-guess I'm trying to say that I don't think this is out of anyone’s ability if they have the desire.
CAN equipment
I am using a Seedtudio v1.2. there is a new version out since I’ve had mine for a while, but I don’ think it does anything significantly different.
http://wiki.seeedstudio.com/CAN-BUS_Shield_V2.0/
This stacks on top of a basic Arduino Uno. And plugs into the car using the OBD-connector and DB9-connector that Seedstudio sells.
There are tons of ways though. I have run into a lot of people who been very successful with the SocketCan, which utilizes Linux and a direct port into a laptop. Since I plan to convert my current rpm/VSS into a CAN message and broadcast, the arduino seemed like the best path for me though.


Different ways to get assist from your unit:
There's several way to tackle this. Some just hook up power(no CANBUS) and have full assist at all times. some hook up what I assume is a pwm circuit and dial in what they want which is the same across all speed levels. My contribution will be(hopefully) adding in the CANBUS communication to the toyota steering ECU and letting the algorithms control assist based on VSS, rpm, steering torque and steering angle. So, as we all know, OEM's spend quite a bit of time tuning the EPS for steering feel. I assume that they spend more time on "feel" for the FRS than they do a Yaris or Prius, so I scooped up a 2014 FRS EPS with ECU. I plan to convert the RPM and VSS from the LS1b GM ECU into CANBUS signals and let it do its thing. That's the plan at least!!!! I'll post more as I make progress, hoping this won't take too long. Below is a quick pic of the EPS in the back seat.



Knowledge sources
So to start with, Waid302 posts in vintage mustang what I consider the best starting place for understanding the project. Its a huge read, but worth it. He provided a ton of pics and diagrams which are enormously helpful-especially if you just want a Prius unit to give full assist.
https://forums.vintage-mustang.com/m...cs-videos.html

dobrostand has a thread in the same forum detailing specifics of the driveability of the system, which led me to believe this might just be worth it.
https://forums.vintage-mustang.com/m...ivability.html

Also on Vintage mustang- Andrewb70, originally known to me as project_GatToGo and who is a huge inspiration to my build, details the specifics of installing in his cougar, but also takes it a step further at getting his dominator to provide VSS to the prius ECU for variable assist. Also pretty much lays out all the details for fab/install that you could ever want,assuming you are skilled with a whizwheelofdeath, lol. Additionaly, he brings up the detail that the ECU needs to run a centering calibration if any of the parts have been mismatched, replaced or otherwise tampered with.
https://forums.vintage-mustang.com/m...s-install.html


I believe those threads should be sufficient to get a Yaris/Prius or Saturn Vue EPS installed and supplying full assist. The nice thing about the Japanese EPS systems is that they supply full assist in default mode if no CAN signals are received. The Vue uses an aftermarket box that dials in "fixed" assist. Lots of people feel fine with that, I might also, but I like being a nerd so I'm looking into supplying the proper CANBus channels.

The next major source of info is some enginerds at the University of Tulsa has published some papers on CANBUS hacking. They provide the engine speed HexID (2C4), and a version of the vehicle speed(610). I'm not entirely sure ID 610 is what the Steering ECU is looking for based on some info I find down below, but we'll get to that. This paper is awesome at showing the methodology for grabbing canbus data and then deciphering it. These guys are the real deal.
http://tucrrc.utulsa.edu/ToyotaCAN.html

Then, Fabio published a youtube video of a camera synced with CANBus data in a 2010 Camry. This allows you to see the structure of the CAN message for RPM (2C4) and Vehicle speed(both “B4” and “610”).
https://www.youtube.com/watch?v=KHRPmjwXF1U


I would say this entire paper is a must-read and is also the most indepth of anything I've found so far. It talks about great details for ford and Toyota steering/braking Canbus interfaces. Specifically, page 41 shows how ID B4(vehicle speed) is not only structured in the way of what bits mean what, but also how to combine them, and the importance of the "checksum" bit at the end of the messages for toyota. If the different nodes don't see the checksum, they will ignore the message all together. I don't know if this is all OEM's or just Toyota.
http://illmatics.com/car_hacking.pdf

[jetmech442]

so the papers/videos above will give a pretty good background on all the details. My knowledge was zero before I started and is at where it is now based on those. Below are some real details for the toyota system I have worked through but not yet implemented. Please feel free to ask questions or comment on whatever. I'm hoping to wire it up soon and start testing it out...

Breaking down the Toyota RPM CAN message.
below is an example of the rpm message {2C4 8 0E 1B 00 19 00 00 92 A2}
2C4 is the message ID and this one happens to mean RPM.
8 is the message size, it will send 8 additional pieces of info.
0E is the first piece of info. In decimal it means 14 ---Protip-the stock calculator app in windows can be changed to "programmer" which allows you to input HEX numbers and it auto translates into decimal.
1B is the 2nd, and it translates into 27
Now those two bites alone don't help or add up to anything, but if you put the HEX together (0E1B) it translates into 3,611-which is the actual rpm!
I don't know what the "19" or "92" mean yet, but the A2 should be the checksum at the end.
To calculate the checksum, it helps to know that the message ID is actually two bits, IDH = 2C and IDL = 04. So to calculate it, add(in HEX calculator) 2C+04+08+0E+1B+19+92 = 1A2. This technique is found in http://illmatics.com/car_hacking.pdf page 9 and 10.

Breaking down the Toyota Vehicle Speed CAN message.
Currently, I am aware of two ID’s that should contain vehicle speed info 610 and B4. The paper from Tulsa shows 610 containing vehicle speed data. The paper from illmatics identifies B4 as the message used by the “combination meter”-that’s the instrument cluster for the rest of us. We don’t know which message the steering ECU is looking for, so I will need to send both(1 at a time), and see which one reduces steering assist as the speed increases.
So to break it down, on page 34 of illmatics, {00B4 8 00 00 00 00 8D 06 66 B5} is equal to 10 mph. we get this by combining 06 and 66 into 0666 which translates from hex to dec as 1,638. We then multiply that dec number by .0062.
1638 *.0062 = 10.15mph.
ID B4 details

The formula for this is found on pg 41 of illmatics, but I’ve rewritten it slightly here to make it easier to understand(IMO).
IDH: 00, IDL: B4, Len: 08, Data: 00 00 00 00 CN B6 B7 CS  
CN = Counter that iterates from 00-FF -I don’t know what the counter does currently, but it goes from 0-255(dec)
B6 = 6th byte of the message
B7 = 7th byte of the message
CS = Checksum
Speed = (B6B7) * .0062 == MPH

ID 610 details

The example here is taken from Fabio’s video @2:07 and @2:09 where you can see the dash is displaying the speed in Kph. It looks to me that the 3rd byte represents Mph. Two such examples seem to confirm this…
610 8 {20 00 10 E4 C0 00 00 00} = 25 kph -------Hex 10 = Dec 16. 16mph = 25kph
610 8 {20 00 07 E4 C0 00 00 00} = 12kph -------Hex 07 = Dec 07. 7mph = 11.3kph(perhaps digital dashes always roundup?)

Tommorow I'll try to post the WDS sheets and how to feed it info.

[raustinss]

Ummmmm.... yeah .. sure , I'd cough up the cash for the turn one box and prevent my brain from melting lol

[Sbeck09]

It's all a little over my head, but that's because my hands aren't on it. Fascinating project you have here. Funny too that you posted since I was just researching to see if the EPAS from a 2011+ mustang could be controlled in a similar fashion.

I'll be keeping tabs on your progress. I'm definitely hoping you succeed with minimal issue.

[andrewb70]

Looking forward to seeing where this goes. You got this!!!

Andrew

[c4racer2]

Hmm. Not sure what the end game is for all of this effort. I have several vehicles with electric steering - probably some of the best on the market - Porsche, Camaro SS, chevy truck, also had a mini.
I’m not feeling it. None are as good as real good old hydraulic based steering. I’ve owned lots of those cars too - old and new. Rack, boxes etc.
part of what I like about older cars is the connection you get to the road from the steering and brakes.
Not to be a Debbie downer. I appreciate the engineering behind this as a EE geek and all !

[stab6902]

Cool project! Having driven lots of cars new and old, I also prefer the feel of hydraulic power steering over electric, but it seems these column mount EPS conversions are getting more popular.

A couple of things to think about:

- Stock FRS's have about 1500 lbs over the front wheels and have 215 mm wide tires. Your A-body certainly weighs more and looks like it has much wider tires. This means your steering effort will be considerably higher (assuming similar box/rack ratios between the two cars).

- What steering box were you thinking of running? You don't want to run a power steering box because the T-bar (used to meter hydraulic assist) has to hit its mechanical stops before "acting" like a manual box. A hydraulic box used without a power steering pump will have a few degrees of "slop" due to T-bar flex. This of course means a manual box is pretty much necessary, but even the quick ratio manual boxes are slow by power steering standards. Ideally you'd probably want a 12.7:1 manual box, but I don't know that those exist.

- I think it's a great idea to feed a VSS signal to the EPS controller. Having variable effort assist is probably the biggest advantage to an EPS setup in my opinion. I have limited experience with EPS CAN interfaces, but I can confirm that the checksums are important. I'm not sure what the fallback/degradation strategy is for your EPS unit, but it could be that it defaults to "full" assist unless you feed it all the signals/checksums it needs to be "happy". One out of range signal or incorrect checksum (and there may be 5+ signals, even though VSS seems like it would be the only relevant one) may be enough to put the unit into fallback state (full assist). If you figure it out though, you'll be a hero!

[rchaskin]

Ummmmm.... yeah .. sure , I'd cough up the cash for the turn one box and prevent my brain from melting lol

HAHAHHAHAHA!!!

[BMR Sales]

I really feel like a Moron after reading all that but I'm interested.

In my Porsche LS6, I had to use a Manual Rack - I would love to drive and not have a Workout at the same time.

[andrewb70]

Hmm. Not sure what the end game is for all of this effort. I have several vehicles with electric steering - probably some of the best on the market - Porsche, Camaro SS, chevy truck, also had a mini.
I’m not feeling it. None are as good as real good old hydraulic based steering. I’ve owned lots of those cars too - old and new. Rack, boxes etc.
part of what I like about older cars is the connection you get to the road from the steering and brakes.
Not to be a Debbie downer. I appreciate the engineering behind this as a EE geek and all !

I actually encouraged Scott to stick with hydraulic steering. Sometimes we do things not because it makes the most sense, but for the challenge of it. I think this is as much the case here as anything else. I don't think there is anything wrong with that motivation.

With my Cougar I had very few options, since I had already installed a TCP manual rack. I liked certain aspects of the manual rack, while hating others. The EPAS has alleviated the negatives of the manual rack, but has also killed off a little bit of what I liked about it. It is definitely a trade off in my opinion. Also keep in mind that my Cougar is a street/strip car. I have 4.5" wide front wheels! So for me, this made a lot of sense. I am taking it a bit further than most people by integrating the speed sensitive variable assist, but this build is way more ambitious.

I also have to mention DCE. They sell what Scott is attempting to pull off. You can buy it right now:
http://www.dcemotorsport.com/Home/EPAS

The issue is that their stuff is not cheap. However, I've had a couple of chats with one of their engineers, and I think they have a pretty good product.

T.C., one of the DCE kits may work very well for you in the Porsche.

Andrew

[67King]

In my Porsche LS6, I had to use a Manual Rack - I would love to drive and not have a Workout at the same time.

I ditched the power steering in both of my race cars (944T and 968), and taking apart my GTO has reminded me how much of a PITA having the hydraulic system in place is, so I'm looking at these if I can find a spare steering column so I don't have to hack up mine (all #'s matching car).

Subscribed to the thread, but when it comes to electronics, the time saved may justify just buying a system rather than doing all of the research to learn how to use these.

[jetmech442]

Ummmmm.... yeah .. sure , I'd cough up the cash for the turn one box and prevent my brain from melting lol

lol, yeah I get it. And I'm certainly not bashing Lee or turnone, I've wanted one of their systems for over 7 years. But the prices are quite high. hopefully, being a thermal engineer I should be able to prevent my brain from melting.

It's all a little over my head, but that's because my hands aren't on it. Fascinating project you have here. Funny too that you posted since I was just researching to see if the EPAS from a 2011+ mustang could be controlled in a similar fashion.

I'll be keeping tabs on your progress. I'm definitely hoping you succeed with minimal issue.

Yeah I think I jumped into the details way too deep before explaining my motivation. I think all the links above help provide a decent foundation, but maybe I should do a better job of summarizing the takeaways to help others save some time. I was thinking about the EPS rack from the 2017 ZL1. People seem to love them and they can be had for 300-600$ on fleabay. I decided to go the FRS route(EPS on column) first because the zl1 rack requires a big garage-time investment in properly installing to eliminate bumpsteer and such, and also because I got the whole thing for 130$ and there is a lot of info on hacking the Toyota can systems for autonomous driving research. When I get it working, if it’s good,not great, I could look at the power on rack solution.

Hmm. Not sure what the end game is for all of this effort. I have several vehicles with electric steering - probably some of the best on the market - Porsche, Camaro SS, chevy truck, also had a mini.
I’m not feeling it. None are as good as real good old hydraulic based steering. I’ve owned lots of those cars too - old and new. Rack, boxes etc.
part of what I like about older cars is the connection you get to the road from the steering and brakes.
Not to be a Debbie downer. I appreciate the engineering behind this as a EE geek and all !

I get it for sure. I don’t have the expectation that my garage mashup is going to be better than a Porsche or SS. But I think it’s going to be better than what I have now, for not much money. I’m okay with the time investment, I love learning new systems and tuning something to get it just right.
Please send any pointers my way you may see, gearheads with EE backgrounds seem like a rarity.

Cool project! Having driven lots of cars new and old, I also prefer the feel of hydraulic power steering over electric, but it seems these column mount EPS conversions are getting more popular.

A couple of things to think about:

- Stock FRS's have about 1500 lbs over the front wheels and have 215 mm wide tires. Your A-body certainly weighs more and looks like it has much wider tires. This means your steering effort will be considerably higher (assuming similar box/rack ratios between the two cars).

- What steering box were you thinking of running? You don't want to run a power steering box because the T-bar (used to meter hydraulic assist) has to hit its mechanical stops before "acting" like a manual box. A hydraulic box used without a power steering pump will have a few degrees of "slop" due to T-bar flex. This of course means a manual box is pretty much necessary, but even the quick ratio manual boxes are slow by power steering standards. Ideally you'd probably want a 12.7:1 manual box, but I don't know that those exist.

- I think it's a great idea to feed a VSS signal to the EPS controller. Having variable effort assist is probably the biggest advantage to an EPS setup in my opinion. I have limited experience with EPS CAN interfaces, but I can confirm that the checksums are important. I'm not sure what the fallback/degradation strategy is for your EPS unit, but it could be that it defaults to "full" assist unless you feed it all the signals/checksums it needs to be "happy". One out of range signal or incorrect checksum (and there may be 5+ signals, even though VSS seems like it would be the only relevant one) may be enough to put the unit into fallback state (full assist). If you figure it out though, you'll be a hero!

Stab-thanks man! I was initially planning on using the 12.7 power box I currently have, but you’ve confirmed my suspicions about the Tbar as to why I shouldn’t do that. I still have the manual box in the attic, it’s not quick ratio, so Ill have to put some thoughts into a solution here, thanks again.

Also about the front tire forces. Yeah I’m running 285’s up front and have close to 1900lbs over the front tires. The ECU is mostly a brain with a motor controller mated to a thick aluminum heat sink plate. If you over heat, it reduces the assist provided. This will be something I keep my eye on as it may need a small comp fan to help keep it under the temp limits.

Without any can channels, Japanese OEMs seem to default to full assist(or so I’ve heard). I for sure know that the steering ECU needs torsion signal, steering angle, VSS and eRPM. But you may be right that it is looking for others. I’ll keep keep that in mind if it isn’t behaving as expected.

I actually encouraged Scott to stick with hydraulic steering. Sometimes we do things not because it makes the most sense, but for the challenge of it. I think this is as much the case here as anything else. I don't think there is anything wrong with that motivation.

With my Cougar I had very few options, since I had already installed a TCP manual rack. I liked certain aspects of the manual rack, while hating others. The EPAS has alleviated the negatives of the manual rack, but has also killed off a little bit of what I liked about it. It is definitely a trade off in my opinion. Also keep in mind that my Cougar is a street/strip car. I have 4.5" wide front wheels! So for me, this made a lot of sense. I am taking it a bit further than most people by integrating the speed sensitive variable assist, but this build is way more ambitious.

I also have to mention DCE. They sell what Scott is attempting to pull off. You can buy it right now:
http://www.dcemotorsport.com/Home/EPAS

The issue is that their stuff is not cheap. However, I've had a couple of chats with one of their engineers, and I think they have a pretty good product.

T.C., one of the DCE kits may work very well for you in the Porsche.

Andrew

It’s true! Andrew tried to talk sense into me, but the little idiot in the back of my head wouldn’t shut up. I really do enjoy this(and I get bored at work sometimes so this fills in the gap lol). This car has always been about making it better by making me better. 8 years ago I didn’t know anything about LS’s, ECU tuning with EFILive, suspension, brakes, steering-but now some of my favorite things about the car are that I tuned it and the adjustable 3 link I designed and installed. 80% of my knowledge came from the great people on this site, so now I’m going to have some fun and hopefully help some others out along the way--yes I’m out of my thermal wheelhouse so to speak, but what fun is doing only what you know?

I ditched the power steering in both of my race cars (944T and 968), and taking apart my GTO has reminded me how much of a PITA having the hydraulic system in place is, so I'm looking at these if I can find a spare steering column so I don't have to hack up mine (all #'s matching car).

Subscribed to the thread, but when it comes to electronics, the time saved may justify just buying a system rather than doing all of the research to learn how to use these.

Yeah King, having pulled the flow control valve several times to fine tune the orifice I just got tired of it. I’m looking forward to variable assist without the mess. My true goal here is to do the research for you guys and provide the code over on GITHUB that can just be used.

[andrewb70]

As far as I can determine, the "failsafe" level of assist is the medium level of assist, at least using the Prius/Yaris hardware and ECU. Time to read the FRS FSM!

Andrew

[andrewb70]

This might be helpful:
https://www.buyautoparts.com/buynow/...Q?xref=2502319

Andrew

[c4racer2]

oh - you would be surprised - lots of EE gearheads out there!

Good luck and keep us posted - I will pipe in if I can help in any way.

[David Pozzi]

I drove an FRS at Streets Of Willow track and found the variable effort distracting. I don't think I'd want it to vary, but maybe full power would be overboosted? Perhaps the dial adjustable conversion would be best.
There are fast ratio conversions for GM manual steering boxes. 16:1 I think.

[jetmech442]

Thanks for the on- track insight David. Your the first trackrat I've heard provide feedback on the system other than the glowing reviews from motortrend. Would you rather the variance be more "step function" like? Perhaps if the rpms are high and vss is above 50 then it sounds be a constant low assist? I say 50 cause that was a good show for Blackhawk farms. I'll definitely have the ability to lie to the steering ecu about rpm and speed to suit my needs if I like.
BTW, always been a big fan of the killer cars you and Mary create.

[67King]

Thanks for the on- track insight David. Your the first trackrat I've heard provide feedback on the system other than the glowing reviews from motortrend. Would you rather the variance be more "step function" like? Perhaps if the rpms are high and vss is above 50 then it sounds be a constant low assist? I say 50 cause that was a good show for Blackhawk farms. I'll definitely have the ability to lie to the steering ecu about rpm and speed to suit my needs if I like.
BTW, always been a big fan of the killer cars you and Mary create.

FWIW, a pretty good friend of mine who instructs both with PCA and at the Porsche center in Atlanta has one that has all but become a dedicated track car, and has no issues with it. Granted, his comparator cars were 944's (Turbo and S2), so much lighter (and 50/50 weight distribution). But FWIW, another anecdote.

[David Pozzi]

I'm sure I could get used to it but it wasn't something I found desirable. Effort was changing mid-corner as I was headed towards an apex, which I really don't like. I'd rather have it up the effort at higher speeds, like 80mph up, than vary it at lower speeds.

[67King]

God that sounds awful. Ian's is a BRZ, I know some stuff was different, wonder if steering tuning was?