A quote form this thread:
www.ft86club.com/forums/showthread.php?t=11810&page=3
Quote:
Originally Posted by mobybrz
Yes, there is a power steering ECU. It is connected to the CAN, the TRQ1 and TRQ2 steering sensors, and an angular resolver (angle sensor). It outputs to the power steering motor.
What you mention between the IS versions isn't (or at least is extremely likely to be) different ECUs. It is more likely different *maps* juts like we are all aware of with ECUTEK on the engine ECU. Theoretically, it should be possible to perform the same reverse engineering work on the power steering ECU to allow maps to be edited or adjusted. I wouldn't be surprised if there is a different EPS map between the FR-S and the BRZ given the differences in suspension.
As it stands, I would imagine the GT86/FR-S/BRZ steering maps based on mostly on speed and driver applied torque. There is might be/likely is an influence from the VSC mode settings, steering angle, gear, and measures of yaw angle (side slip/rotation, the same measure that drives VSC intervention).
To give an example, one could theoretically create a map that is designed to assist the driver i an accident avoidance manuever on the highway. The ECU could detect a likely avoidance maneuver and provide an increased steering torque initially (effecitvely increasing the drivers turning rate) before ramping down the provided torque (slowing the drivers turning rate) to prevent an overcorrection and help dampen any potential for a tank slapper. You could use (again theoretically) anything coming over the CAN to influence the map.
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And that sounds perfectly reasonable and enlightened to me.
I still think there's an open question here. Is the power steering mechanically able to make the steering
harder than it'd be if it just lost power?
I mean, it really shouldn't. I've seen software glitches in my car, a couple of times it flashed a lot of warning lamps and wouldn't start before I got out, locked the doors with the remote, opened it and got in again.
And that's fine. A software glitch that will kill me is not.