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By the way I don't know how an on board computer can work around problems except to shut down systems that have problems, where shutting down a system is safer than leaving a defective system active.
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Yes, that's basically it. For example, fuel injection systems with mass air flow sensors may respond to an airflow sensor failure by ignoring it, and using more crude speed and air density method. With a wheel speed sensor I can't imagine a workaround which would not lose functionality and justify keeping the trouble
light on; for instance, ABS could ignore that wheel and only work to relieve lockup on the other three... but that means one wheel potentially locking up, a significant loss of functionality.
The possibility of an intermittent fault seems more likely, and thus the value of error codes.
The connection with the controller just seems like way too much of a coincidence to me. I wonder if there is an intermittent connection in the controller wiring, rather than an intermittent fault in an actual sensor? On the other hand, unwanted ABS action does seem consistent with a wheel speed signal saying the wheel has locked up, when it really hasn't. Maybe a sensor
is intermittently faulty, and the brake controller makes it seem like the
brakes are being applied so the problem becomes apparent - that would be both a controller installation problem
and a real sensor problem!