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.
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HOMESERVICE MANUALSTOYOTA2004TUNDRA 4WD V8-4.7L (2UZ-FE)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSMAIN RELAY (COMPUTER/FUEL SYSTEM)TESTING AND INSPECTION
2004 Toyota Tundra 4WD V8-4.7L (2UZ-FE)
Main Relay (Computer/Fuel System): Testing and Inspection
2004 Toyota Tundra 4WD V8-4.7L (2UZ-FE)SECTION Testing and Inspection
INSPECTION
1. REMOVE RELAY BOX COVER
2. REMOVE EFI MAIN RELAY (Marking: EFI)
3. INSPECT EFI MAIN RELAY
a. Inspect the relay continuity.
1. Using an ohmmeter, check that there is continuity between terminals 1 and 2.
If there is no continuity, replace the relay.
2. Check that there is no continuity between terminals 3 and 5.
If there is continuity, replace the relay.
b. Inspect the relay operation.
1. Apply battery voltage across terminals 1 and 2.
2. Using an ohmmeter, check that there is continuity between terminals 3 and 5.
If there is no continuity, replace the relay.
4. REINSTALL EFI MAIN RELAY
5. REINSTALL RELAY BOX COVER
1. REMOVE RELAY BOX COVER
2. REMOVE EFI MAIN RELAY (Marking: EFI)
3. INSPECT EFI MAIN RELAY
a. Inspect the relay continuity.
1. Using an ohmmeter, check that there is continuity between terminals 1 and 2.
If there is no continuity, replace the relay.
2. Check that there is no continuity between terminals 3 and 5.
If there is continuity, replace the relay.
b. Inspect the relay operation.
1. Apply battery voltage across terminals 1 and 2.
2. Using an ohmmeter, check that there is continuity between terminals 3 and 5.
If there is no continuity, replace the relay.
4. REINSTALL EFI MAIN RELAY
5. REINSTALL RELAY BOX COVER
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.