Diagnostics, Scan Tools, and DTC Interpretation
ADAS diagnostics rely on scan tools that communicate with multiple modules, read and clear DTCs, view live data, and initiate calibrations and relearns. Candidates must understand DTC structure-system, component, and fault type-and the difference between a hard fault (present) and a stored/history fault (intermittent). Many ADAS faults are set by blocked or misaligned sensors, network communication errors, or voltage issues rather than failed hardware.
Know the diagnostic workflow: verify the complaint, check for related DTCs across modules (a camera fault may set codes in several ECUs), inspect wiring and connectors, verify power and ground, and confirm sensor cleanliness and mounting before replacing parts. Scan tools must support the specific make/model and calibration routines; a generic code reader often cannot perform ADAS calibrations or bidirectional tests.
Traps: clearing codes without repairing the cause (the fault returns); replacing a sensor when the real issue is a misalignment or blocked lens; ignoring communication DTCs that point to a network problem; assuming a code in one module means that module is at fault. Another trap is post-repair-after body work, codes may persist until calibration is completed.
Worked example: A forward camera sets a "blocked/performance" code. Before replacement, check the windshield for dirt, cracks, or stickers in the camera's field, verify mounting and connector, then attempt calibration. If calibration succeeds, the code clears-no part needed. Use freeze-frame and live data to confirm the sensor sees the world correctly.