TCS Self-diagnosis

The ABS/TCS control unit is equipped with a main CPU and a sub-CPU. Each CPU checks the other for problems.
The CPUs check the circuit of the system.
Self-diagnosis can be classified into two categories:
- Initial diagnosis: Done right after the engine starts and until the ABS or TCS indicator goes off
- Regular diagnosis: Done right after the initial diagnosis until the ignition switch is turned OFF
When a problem is detected by self-diagnosis, the ABS/TCS control unit shifts to fail-safe mode.