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Use the first starting split—cranks or does not crank—to choose the correct electrical, authorization, fuel, ignition, or mechanical diagnostic path.
beginnerSeparate fuel, spark, compression, timing, and security-system faults with a test-first process.
IntermediateSeparate missing ignition, fuel delivery, control, synchronization, and mechanical evidence after the engine is confirmed to crank.
Test-first procedureUse warning behavior, scan context, cylinder pattern, and controlled contribution evidence to separate ignition, fuel, air, and mechanical branches.
Test-first procedureSeparate start-request, interlock, cable, ground, solenoid, and starter-motor evidence before bypassing the circuit or replacing the starter.
Test-first procedureThe starting system must authorize the request and deliver high current long enough to rotate the engine. A no-crank condition is different from an engine that cranks normally but does not run.
System guideThe fuel system stores and meters fuel under controlled conditions. A no-start, lean code, odor, or hesitation can involve supply, command, air measurement, electrical control, mechanical condition, or vapor management.
System guideAI guidance is separate from verified IAR sources.
Feedback stays on this device and isn’t sent to IAR. Vehicle identifiers are redacted before saving.