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.
Main Relay Control: Notes
When the ignition switch is turned ON, battery voltage is applied from the ignition switch to the ECU, turning ON the ignition power transistor and energizing the MFI control relay coil. This turns the MFI control relay switch ON, and supplies power from the battery to the ECU through the MFI control relay switch.
After the ignition switch is turned OFF, battery voltage is supplied to Main relay for 8 seconds. ECU remembers and calculates the data.
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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