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 (Computer/Fuel System): Testing and Inspection
2003 Hyundai Tiburon L4-2.0LSECTION Testing and Inspection
MFI CONTROL RELAY
When the ignition switch is on, battery power is supplied to the ECM, the injectors, the mass air flow sensor, etc. While the ignition switch is turned on, current flows from the ignition switch through the current relay coil to ground.
MFI CONTROL RELAY INSPECTION
1. Check the continuity of relay contacts between terminals 5 (+) and 1 (-).
2. If faulty, replace the MFI control relay.
When the ignition switch is on, battery power is supplied to the ECM, the injectors, the mass air flow sensor, etc. While the ignition switch is turned on, current flows from the ignition switch through the current relay coil to ground.
Circuit Diagram:
Harness Inspection Procedures:
MFI CONTROL RELAY INSPECTION
1. Check the continuity of relay contacts between terminals 5 (+) and 1 (-).
2. If faulty, replace the MFI control relay.
RENDER: 1.0x
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.