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 DIAGNOSISENGINE, COOLING AND EXHAUSTCOOLING SYSTEMRELAYS AND MODULES - COOLING SYSTEMRADIATOR COOLING FAN CONTROL MODULETESTING AND INSPECTION
2006 Lexus RX 400h AWD V6-3.3L (3MZ-FE) Hybrid
Radiator Cooling Fan Control Module: Testing and Inspection
2006 Lexus RX 400h AWD V6-3.3L (3MZ-FE) HybridSECTION Testing and Inspection
COOLING FAN ECU
ON-VEHICLE INSPECTION
1. CHECK COOLING FAN ECU (No. 1 and No. 2)
a. Inspect the input voltage.
(1) Disconnect the cooling fan ECU connectors.
(2) Turn the ignition switch On.
(3) Measure the voltage between terminals +B and GND.
Standard voltage: 8 to 15 V
If the voltage is not as specified, check the fusible links, fuses, wire harness and fan relay.
(4) Reconnect the connectors.
HINT: Wire harness condition is diagnosed by cooling fan operation.
b. Check the HV control ECU power source.
c. Check RFC1 and RFC2 signal generation.
NOTICE: Perform this inspection when coolant temperature is 82°C (180°F).
(1) Connect an oscilloscope to terminals RFC1 (RFC2) and E1 of the HV control ECU.
(2) Check the signal generation and measure the current according to the value(s) in the table.
HINT:
^ If RFC1 (RFC2) signal is not as specified, replace the HV control ECU.
^ When the fan amperage has a problem even if the RFC1 (RFC2) signal that has no problem, replace the cooling fan ECU.
ON-VEHICLE INSPECTION
1. CHECK COOLING FAN ECU (No. 1 and No. 2)
a. Inspect the input voltage.
(1) Disconnect the cooling fan ECU connectors.
(2) Turn the ignition switch On.
(3) Measure the voltage between terminals +B and GND.
Standard voltage: 8 to 15 V
If the voltage is not as specified, check the fusible links, fuses, wire harness and fan relay.
(4) Reconnect the connectors.
HINT: Wire harness condition is diagnosed by cooling fan operation.
b. Check the HV control ECU power source.
c. Check RFC1 and RFC2 signal generation.
NOTICE: Perform this inspection when coolant temperature is 82°C (180°F).
(1) Connect an oscilloscope to terminals RFC1 (RFC2) and E1 of the HV control ECU.
(2) Check the signal generation and measure the current according to the value(s) in the table.
HINT:
^ If RFC1 (RFC2) signal is not as specified, replace the HV control ECU.
^ When the fan amperage has a problem even if the RFC1 (RFC2) signal that has no problem, replace the cooling fan ECU.
RENDER: 1.0x
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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.