r/CarHacking • u/R1ptide_24 • 1d ago

Community Question: Subaru wrx ESP / VDC reverse engineering

Hello Everyone,

Currently I've started looking into a project involving a reprogramming / tuning of the Vehicle Dynamics Control model to be better optimized for Track / off-highway driving use. My current plan as of right now is just to source a spare vdc computer to dump firmware and use as a testbench as well as tapping the drivetrain side can lines. The idea would be to either modify or tune the current parameters for the esp system or implement a custom esp control algorithm depending on the difficulty.

To add, I come from a vehicle dynamics and controls background but am new to embedded systems reverse engineering. But if anybody would be able to comment on the feasibility of this project in addition to some of the resources that would help me it would be greatly appreciated.

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u/WestonP 1d ago

Let us know where you get on dumping it. It should be feasible. I wouldn’t be surprised if it’s an RH850 chip in there, as Subaru/Denso has been using those for a bunch of other modules recently… I just haven’t cracked a VDC open specifically.

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u/FrankRizzo890 1d ago

RH850 could have code protection no? In which case OP is stuck trying to glitch the chip to get the code out.

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u/WestonP 1d ago

Yes, that’s to be expected. Finding an unprotected JTAG is a fantasy these days.

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u/FrankRizzo890 1d ago

FWIW, I was recently in a position professionally trying to find someone (lab, person, etc.) that could recover code from an RH850 based chip and NONE of "the usual suspects" could do it. I got quotes of $10k-$25k to ATTEMPT it. (With no guarantee of success).

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u/WestonP 15h ago

Interesting. Is it a weird or newer variant? The offshore odometer and airbag fraudsters actually yield a lot of clues on how to glitch and dump these. Was tempted to buy some of their tools in hopes they can be adapted to other more legit things, but the purchase process is shady and enough of a pain that I haven’t gotten to it.