On Saturday, January 27, 2018 at 6:21:23 PM UTC-10, wrote:
>
> In this car the brake fail bulb is turned on directly by master cylinder switch.
> The ECU only controls a few lamps like "engine", low fuel.

You could try disconnecting the master cylinder switch and forcing the light to come on and see if there's any speed capping. My guess is that the car companies don't want you to limp-home if your brake fails so no limp-home program is implemented when this occurs. Of course, what's the worst that could happen? I limped home when my brakes failed. Going over the mountain was scary!