Cooling Fan Control System: Notes

1. Coolant temperature should be less than 185°F (85°C) on ES250 or less than 181°F (83°C) on LS400. Turn ignition on. Cooling fans should not rotate. If cooling fans rotate, check cooling fan relays and water temperature sensor (ES250) or water temperature switch (LS400). Check for damaged connectors and an open circuit between cooling fan relay and water temperature sensor/switch.
2. Disconnect water temperature sensor/switch connector. See Fig 1 or Fig 2. With ignition on, cooling fans should operate. If cooling fans do not operate, check engine main relay and fuse. Check cooling fan motors. Also check cooling fan relays and water temperature sensor/switch. Check for damaged connectors or an open circuit between cooling fan relay and water temperature sensor/switch. If okay, go to step 3) for ES250 or step 4) for LS400.
   Fig 1: Locating Cooling Fan System Components (ES250)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   Fig 2: Locating Cooling Fan System Components (LS400)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. On ES250, reconnect water temperature sensor. Start engine. Warm engine to operating temperature. Cooling fans should operate at low speed. If cooling fans do not operate at low speed, replace water temperature sensor.
4. On all models, reconnect water temperature sensor/switch. Warm engine to more than 199°F (93°C). Cooling fans should operate at high speed. If cooling fans do not operate at high speed, replace water temperature sensor/switch.
5. On LS400, cooling fan should also activate when A/C pressure switch indicates high A/C line pressure. Refer to LS400 A/C PRESSURE SWITCH  under COOLING FAN CONTROL SYSTEM.