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.
Circuit Description
The circuit opening relay provides ignition positive voltage to the fuel pump. The circuit opening relay is controlled by the Powertrain Control Module (PCM) and receives ignition positive voltage from the EFI relay. PCM monitors the crank signal circuit for voltage when the ignition switch is in the START (engine cranking) position. When the crank signal circuit indicates the engine is cranking the PCM energizes the circuit opening relay. PCM also energizes the circuit opening relay whenever reference pulses from the Crankcase Position (CKP) sensor circuit are detected. If the crank signal circuit does NOT indicate the engine is cranking the PCM will energize the circuit opening relay based only upon reference pulses.
NO RELATED
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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.