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 MANUALSLEXUS1999RX 300 AWD 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
1999 Lexus RX 300 AWD V6-3.0L (1MZ-FE)
Main Relay (Computer/Fuel System): Testing and Inspection
1999 Lexus RX 300 AWD V6-3.0L (1MZ-FE)SECTION Testing and Inspection
1. REMOVE CIRCUIT OPENING RELAY (Marking: CIR OPN)
2. INSPECT CIRCUIT OPENING 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 CIRCUIT OPENING 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 CIRCUIT OPENING 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.