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The physical TJA button arms MRCC on bus 0 as a side effect of the press the driver declared as the lateral switch; the frame reaches bus-0 ECUs directly, so the arm cannot be prevented. When MRCC was off before the press, the controller answers the arm with the same MRCC master press the driver would use: one exact active-low CRZ_BTNS shape, one frame per body-paced 200 ms slot, at most three frames per unreconciled arm, never sent while PEDALS reads disarmed, stopped by raw PEDALS confirming the arm is gone. The body drops discrete presses faster than one per 200 ms, and the disarm reaches PEDALS ~80 ms after a press plus the 50 ms confirm, so the 200 ms slot keeps the stand-down ahead of the next press. The driver's own cruise presses, a held TJA press, and radar or stock-ECU transitions all stand down, and ICBM stands down through the whole TJA hold: the wheel's press pattern owns the counter stream until release. A car that never arms through the press stands down after 1 s of brake-free time, since PEDALS cannot witness an arm under braking. The wheel's MRCC master press publishes mainCruise on declared cars, held unpressed until the wheel's first frame. The new safety permission is the exact frame shape gated on the button declaration plus live cruise arming; an undeclared car changes nothing. Validation: 572 mazda car tests + 283 mazda safety tests host-side, ruff clean.
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Problem
On a TJA-equipped car the wheel TJA button arms MRCC as a side effect of the press, and the wheel's frame reaches bus-0 ECUs directly, so the arm cannot be prevented. The driver pressed the lane keeping button and got a cruise state they did not ask for.
Fix
Validation
Credit
@chinna244
AI Usage
Disclaimer: GLM-5.3 by Z.ai was used to help develop, debug, and document this submission. All changes were reviewed and validated by me.