Cooling Fan Circuit

2UR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: Cooling Fan Circuit

Cooling Fan Circuit

DESCRIPTION

Based on the vehicle condition, the cooling fan ECU controls the cooling fan so that it operates at an optimum speed. The cooling fan ECU controls the cooling fan speed according to the duty ratio sent from the multiplex network front light ECU (front controller). The duty ratio is determined by selecting the highest speed from the fan speeds requested by the various ECUs via CAN communication.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER OR TECHSTREAM (COOLING FAN)
(a) Connect the intelligent tester or Techstream to the DLC3.
(b) Turn the power switch ON (IG).
(c) Enter the following menus:
(1) Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / COOLING FAN.
(2) Techstream - Select: Powertrain / Engine and ECT / Active Test / Control the Electric Cooling Fan.
(d) Check the cooling fan operation.
OK:
Cooling fan operates according to the Active Test.
NG -- INSPECT COOLING FAN ECU (POWER SOURCE)
OK -- CHECK INTERMITTENT PROBLEMS
2. INSPECT COOLING FAN ECU (POWER SOURCE)





(a) Disconnect the cooling fan ECU connector.
(b) Turn the power switch ON (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- INSPECT FUSE (FAN NO. 1 AND E/G RM-IG1-1)
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (MULTIPLEX NETWORK FRONT LIGHT ECU - COOLING FAN)





(a) Disconnect the multiplex network front light ECU (front controller) connector.
(b) Disconnect the cooling fan ECU connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. INSPECT COOLING FAN MOTOR





(a) Disconnect the cooling fan motor connectors.
(b) Apply the battery voltage to the terminals of the cooling fan motor connectors.
(c) Check the cooling fan operation.
OK:






NG -- REPLACE COOLING FAN MOTOR
OK -- Continue to next step.
5. INSPECT COOLING FAN ECU





(a) Disconnect the cooling fan ECU connectors.
(b) Apply the battery voltage to the terminals of the cooling fan ECU.
(c) Check the cooling fan operation.
OK:






NG -- REPLACE COOLING FAN ECU
OK -- REPLACE MULTIPLEX NETWORK FRONT LIGHT ECU (FRONT CONTROLLER)
6. INSPECT FUSE (FAN NO. 1 AND E/G RM-IG1-1)





(a) Replace the FAN NO. 1 fuse from the No. 1 fusible link block assembly.





(b) Replace the E/G RM-IG1-1 fuse from the engine room No. 2 relay block.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- CHECK HARNESS AND CONNECTOR (MULTIPLEX NETWORK FRONT LIGHT ECU (FRONT CONTROLLER) - COOLING FAN
OK -- Continue to next step.
7. INSPECT COOLING FAN RELAY (FAN NO. 1)
(a) Inspect the FAN NO. 1 relay Testing and Inspection.
NG -- REPLACE RELAY
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (COOLING FAN ECU - BATTERY)
8. CHECK HARNESS AND CONNECTOR (MULTIPLEX NETWORK FRONT LIGHT ECU (FRONT CONTROLLER) - COOLING FAN





(a) Disconnect the multiplex network front light ECU (front controller) connector.
(b) Disconnect the cooling fan ECU connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
9. INSPECT COOLING FAN MOTOR





(a) Disconnect the cooling fan motor connectors.
(b) Apply the battery voltage to the terminals of the cooling fan motor connectors.
(c) Check the cooling fan operation.
OK:






NG -- REPLACE COOLING FAN MOTOR
OK -- Continue to next step.
10. INSPECT COOLING FAN ECU





(a) Disconnect the cooling fan ECU connectors.
(b) Apply the battery voltage to the terminals of the cooling fan ECU.
(c) Check the cooling fan operation.
OK:






NG -- REPLACE COOLING FAN ECU
OK -- REPLACE FUSE