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Old 01-17-2020, 05:20 PM   #579
murfnamedsmurf
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Member#: 320178
Join Date: May 2012
Vehicle:
2012 STi

Default SAS scaler to fix over-active VDC

Quote:
Originally Posted by chinyue View Post
I'd like to report that I have created a steering angle sensor proxy and seems to have the VDC issue solved.

I have the 15 STI steering rack installed on my 11 Forester XT (SH9), it was really nice except that VDC kicks in engaging breaks when doing hard turns. The issue persists even you turned the VDC off, so I think this is what gsrcrxsi said that you cannot completely turn VDC off on WRX/FXT.

It's quite annoying so I started looking for solutions and decided to create a device to scale up the steering angle signals. The steering angle for stock SH9 is 580 degrees if you turn the wheel all the way left, and it's 440 degrees for 15 STI steering rack. So I need to scale up around 31%.

I used Arduino Uno with 2 CAN BUS shields, intercepts messages from steering angle sensor, scales the angle up, and forwards. VDC reads messages from steering angle sensor and sends out its own messages (probably for ECU to read) with angle info in it. So I borrowed a Subaru DST-i which can be used to diagnose VDC and read the angle sent by VDC and confirmed that VDC accepts the scaled-up angles. Road test also confirmed that VDC no longer kicks in in those corners it used to.







The same steering angle sensor is used on 08-14 STI/WRX/FXT so I think the SAS proxy approach should work on all these models.

For those who are having ongoing problems and want to create a similar project, I've created a new how-to guide since it seems all the old posts either have broken links, photos, or the host forums no longer exist

https://www.subaruforester.org/threa...rduino.809292/
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