Choose the Correct Diagnostic Path
No Crank + Code 12
This generally indicates an issue with the starter or cranking circuit. Inspect the battery, cables, grounds, fuses, starter relay, wiring, starter motor, and related cranking components. The video walks through the steps used to diagnose a defective starter.
Cranks + Code 12
This indicates an issue with the crankshaft-position sensor or its circuit. Inspect the sensor, connector, wiring, and signal circuit before replacing components.
Test before replacing parts: A stored Code 12 does not automatically mean the starter motor or crankshaft-position sensor is defective. Confirm the symptom and test the applicable circuit first.