CURATED AUTOMOTIVE DIRECTORY
Fault Diagnosis
Diagnostic methods for converting a complaint into evidence, tests, decisions, and verification.
ARTICLES & MATERIALS
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Turn a Customer Complaint Into a Testable Symptom
Good diagnosis begins by translating words such as “hesitates,” “dead,” or “vibrates” into an operating condition that another person can reproduce.
Read guideFreeze-Frame Data: A Reading Order That Prevents Guessing
Freeze frame is a snapshot near code detection. Its value comes from code status, units, operating state, and relationships between parameters.
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The Five-Question Component Test Plan
Before replacing a component, ask whether it has the right power, ground, input, command, and measurable output or feedback.
Read guideA/B Testing in Vehicle Diagnosis
Comparing a known-good condition, bank, cylinder, side, speed, temperature, or substituted load can reveal differences without relying on memory.
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Verify a Repair With the Original Test
A cleared lamp is not proof. Verification repeats the complaint conditions, the failed measurement, and any relevant monitor or self-test.
Read guideUse these guides to plan checks, not to replace model-specific service information. Stop when a procedure involves unsupported lifting, pressurized fuel, pyrotechnic restraints, refrigerant recovery, or high-voltage isolation beyond your training and equipment.