Radiator Cooling Fan: Description and Operation

SYSTEM OUTLINE

FAN MOTOR OPERATION (1MZ- FE)
With the ignition SW turned on, the current through the ECU-IG fuse flows to the FAN NO.1 relay (Coil side), FAN NO.2 relay (Coil side) and FAN NO.3 relay (Coil side). Furthermore, the current through the FAN NO.1 relay (Coil side) or the FAN NO.2 relay (Coil side) flows to TERMINAL 3 of the A/C single pressure SW to TERMINAL 2 to TERMINAL 2 of the water temp. SW no.1 to TERMINAL 1 to GROUND, causing the FAN NO.1 relay to turn off and the FAN NO.2 relay to turn on.

1. LOW SPEED OPERATION (1MZ-FE)
Only when the A/C system is activated or the water temp. SW no.2 is turned on, the AC condenser fan motor and the radiator fan motor rotates at low speed.
When the A/C system is activated, the current from ECU-IG fuse flows to the FAN NO.3 relay (Coil side) to TERMINAL 1 of the diode (A/C) to TERMINAL 2 to TERMINAL 12 of the A/C amplifier (Manual A/C), TERMINAL 2 of the A/C control assembly (Automatic A/C), causing the FAN NO.3 relay to turn on. As a result, the current through the CDS fuse flows to TERMINAL 2 of the A/C condenser fan motor to TERMINAL 1 to TERMINAL 3 of the FAN NO.2 relay to TERMINAL 5 to TERMINAL 5 of the FAN NO.3 relay to TERMINAL 3 to TERMINAL 2 of the radiator fan motor to TERMINAL 1 to GROUND. As this flowing in series for the motors, the motors rotate at low speed.
When the water temp. SW no.2 is turned on, the current from ECU-IG fuse flows to the FAN NO.3 relay (Coil side) to TERMINAL 1 of the water temp. SW no.2 to GROUND, causing the FAN NO.3 relay to turn on. As a result, the current through the CDS fuse flows the same route as above, rotating the motors at low speed.

2. HIGH SPEED OPERATION (1MZ-FE)
Only when the A/C single pressure SW is turned off or the water temp. SW no.1 is turned off, the A/C condenser fan motor and the radiator fan motor rotate at high speed.
When the A/C single pressure SW is turned off, the current from the RDI fuse flows to the FAN NO.1 relay (Point side) to TERMINAL 2 of the radiator fan motor to TERMINAL 1 to GROUND. At the same time, the current from the CDS fuse flows to TERMINAL 2 of the A/C condenser fan motor to TERMINAL 1 to TERMINAL 3 of the FAN NO.2 relay to TERMINAL 4 to GROUND.
As the current flowing in parallel for the motors as above, the motors rotate at high speed.