Toyota Prius Gen3 - Electric Power Steering

[Monstrobolaxa]

I am working on a project that is looking to install an electric power steering to another vehicle. I have come across the Prius Gen3 electric power steering that has a fail-safe mode, i.e., if the steering control unit is unplugged the power steering carries on working at a given load, independent of the vehicle speed. On the Gen2 Yaris there is a similar system, but it requires the vehicle speed signal to be life for it to go into the fail-safe without the motor control unit.

Now the question is, does anyone know if the Gen4 Prius electric power steering has the same fail-function function? If not what are the differences? And does anyone have the pin-outs for the power steering connectors?

Thank you for the help.

[flash22]

It's been done plenty of times, it's a very common upgrade for classics, a quick google

https://www.therangerstation.com/tech/toyota-electric-power-steering-eps-conversion/

https://ls1tech.com/forums/suspension-brakes/1848775-35-electric-power-steering-fail-safe-no-ebay-module-no-caster-issues-4.html

https://www.motortrend.com/how-to/150-electric-power-steering-junkyard-prius-delivers/

https://www.toymods.org.au/forums/threads/79652-Electric-power-steering

 

yes EPS always needs a vss to function correctly as it changes the assistance depending on the speed

for wiring diagrams, try

https://cardiagn.com/wiring/

 

[Monstrobolaxa]

Hello flash22, Thanks for the reply. 

I had seen the 1st link you've shared...I was just wondering if the fail-safe is still present in the Gen4 as the used ones found on ebay/parts breakers are likely to be lower mileage.

 

[flash22]

46 minutes ago, Monstrobolaxa said:

Hello flash22, Thanks for the reply. 

I had seen the 1st link you've shared...I was just wondering if the fail-safe is still present in the Gen4 as the used ones found on ebay/parts breakers are likely to be lower mileage.

It will go to fail-safe if the torque sensor and steering angle sensors are not seen by the ecu iirc these can be bypassed, i did look into this many years ago for a friend

[Monstrobolaxa]

Ok cool. That helps. 

Basically looking at running an EPAS in fail-safe mode with the control unit disconnected....R&D project. 

[flash22]

Just looked at the later 15 on specs, the fail-safe either reduces assist or turns the eps off completely

It looks like after 2009 they changed the fail-safe, if the ecu doesn't see the angle or position it turns off

[Monstrobolaxa]

Brilliant, thanks for the heads up!