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 MANUALSLEXUS2006RX 400H AWD V6-3.3L (3MZ-FE) HYBRIDREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSRELAYS AND MODULES - COMPUTERS AND CONTROL SYSTEMSENGINE CONTROL MODULETESTING AND INSPECTIONCOMPONENT TESTS AND GENERAL DIAGNOSTICS
2006 Lexus RX 400h AWD V6-3.3L (3MZ-FE) Hybrid
Component Tests and General Diagnostics
2006 Lexus RX 400h AWD V6-3.3L (3MZ-FE) HybridSECTION Component Tests and General Diagnostics
ECM Power Source Circuit
DESCRIPTION
When the engine switch is turned to on, the battery voltage is applied to terminal IGSW of the ECM (Included in HV Control ECU). The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the IGCT relay and supplying power to terminal +B of the ECM.
If the engine switch is turned to off, the ECM holds the IGCT relay ON for a maximum of 2 seconds to allow for the initial setting of the throttle valve.
When the ignition switch is turned ON, voltage from the ECM's MREL terminal flows to the IGCT relay. This causes the contacts of the IGCT relay to close, which supplies power to terminal +B or +B1 of the ECM.






INSPECTION PROCEDURE
DESCRIPTION
When the engine switch is turned to on, the battery voltage is applied to terminal IGSW of the ECM (Included in HV Control ECU). The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the IGCT relay and supplying power to terminal +B of the ECM.
If the engine switch is turned to off, the ECM holds the IGCT relay ON for a maximum of 2 seconds to allow for the initial setting of the throttle valve.
When the ignition switch is turned ON, voltage from the ECM's MREL terminal flows to the IGCT relay. This causes the contacts of the IGCT relay to close, which supplies power to terminal +B or +B1 of the ECM.
Wiring Diagram:
Step 1-2:
Step 3-4:
Step 5-6:
Step 7-8:
Step 9:
INSPECTION PROCEDURE
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.