Leganza CDX L4-2.2L DOHC D-TEC MFI (1999)
Radiator Cooling Fan Motor: Testing and Inspection
Engine Cooling Fan Circuit Check
Circuit Description
The engine cooling fan circuit operates the main cooling fan and the auxiliary cooling fan. The cooling fans are controlled by the engine control module
(ECM) based on inputs from the engine coolant temperature (ECT) sensor and the air conditioning pressure (ACP) sensor. The ECM controls the low
speed cooling fan operation by internally grounding the ECM connector terminal C13. This energizes the low speed cooling fan relay and operates the
main cooling fan and the auxiliary cooling fan at low speed as the cooling fans are connected in a series circuit. The ECM controls the high speed
cooling fan operation by internally grounding the ECM connector terminal C13 and the ECM connector terminal C12 at the same time. This energizes
the low speed cooling fan relay, the high speed cooling fan relay, and the series/parallel cooling fan relay resulting in high speed fan operation as the
cooling fans are now connected in a parallel circuit.
Diagnostic Aids
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If the owner complained of an overheating problem, it must be determined if the complaint was due to an actual boil over, or the engine coolant
temperature gauge indicated overheating. If the engine is overheating and the cooling fans are on, the cooling system should be checked.
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If the engine fuse block fuses EF3 or EF8 become open (blown) immediately after installation, inspect for a short to ground in the wiring of the
appropriate circuit. If the fuses become open (blown) when the cooling fans are to be turned on by the engine control module (ECM), suspect a
faulty cooling fan motor.
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The ECM will turn the cooling fans on at low speed when the coolant temperature is 93 °C (199 °F). The ECM will turn the cooling fans off when
the coolant temperature is 90 °C (194 °F).
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The ECM will turn the cooling fans on at high speed when the coolant temperature is 97 °C (207 °F). The ECM will change the cooling fans from
high speed to low speed when the coolant temperature is 94 °C (201 °F).
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The ECM will turn the cooling fans on at low speed when the AC system is on. The ECM will change the cooling fans from low speed to high
speed when the high side AC pressure is 1,859 kPa (269 psi) then return to low speed when the high side AC pressure is 1,449 kPa (210 psi).
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The cooling fan circuit can be checked quickly by disconnecting the ECM white connector and grounding the connector terminal C13. This should
create low speed cooling fan operation with the ignition ON. By grounding the ECM connector terminals C13 and C12 and turning the ignition
