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 MANUALSTOYOTA2000SIENNA LE V6-3.0L (1MZ-FE)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSRELAYS AND MODULES - COMPUTERS AND CONTROL SYSTEMSMAIN RELAY (COMPUTER/FUEL SYSTEM)TESTING AND INSPECTION
2000 Toyota Sienna LE V6-3.0L (1MZ-FE)
Main Relay (Computer/Fuel System): Testing and Inspection
2000 Toyota Sienna LE V6-3.0L (1MZ-FE)SECTION Testing and Inspection
1. REMOVE EFI MAIN RELAY (Marking: EFI)

2. INSPECT EFI MAIN RELAY CONTINUITY

a. Using an ohmmeter, check that there is continuity between terminals 1 and 2.
If there is no continuity, replace the relay.
b. Check that there is no continuity between terminals 3 and 5.
If there is continuity, replace the relay.
3. INSPECT EFI MAIN RELAY OPERATION
a. Apply battery voltage across terminals 1 and 2.

b. 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
2. INSPECT EFI MAIN RELAY CONTINUITY
a. Using an ohmmeter, check that there is continuity between terminals 1 and 2.
If there is no continuity, replace the relay.
b. Check that there is no continuity between terminals 3 and 5.
If there is continuity, replace the relay.
3. INSPECT EFI MAIN RELAY OPERATION
a. Apply battery voltage across terminals 1 and 2.
b. 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
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:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.