Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Chart A-1, No Check Engine Light: Notes
CHECK ENGINE light should always be on steady when ignition is on and engine is not running. Battery voltage is supplied directly to light bulb. ECM controls light and turns it on by providing a ground path through Purple/Yellow wire to ECM.
- Checks to see if ECM is receiving power.
- Checks to see if ECM is faulty.
- Checks for an open in Blue/Black wire between main relay and ECM.
- Checks for a good ECM ground.
- Checks for an open in Black/White wire to instrument panel and Purple/Yellow wire to ECM.
- Checks if main relay is receiving power.
- Checks to see if main relay coil is receiving power.
- Checks to see if main relay or ECM is faulty, or for an open in Blue wire between main relay and ECM.
- Checks for a faulty ignition switch or an open in Black/Blue or Black/White wires to IG-COIL METER fuse.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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