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Home >> Lexus >> 1993 >> SC 400 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Miscellaneous Controls >> Cooling Fan >> Electronic Cooling Fan System (GS300 & LS400)
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Electronic Cooling Fan System (GS300 & LS400)

  1. Coolant temperature should be less than about 180-190°F (83-88°C). Turn ignition on. Cooling fans should not rotate. If cooling fans rotate, check cooling fan relays and coolant temperature switch. Check for damaged connectors and an open circuit between cooling fan relay and coolant temperature switch.
  2. Disconnect coolant temperature switch connector. See Figure or Figure. With ignition on, cooling fans should operate. If cooling fans do not operate, check engine main relay and fuse and replace as necessary. If main relay and fuse are okay, check cooling fan motors and replace as necessary. If cooling fan motors are okay, check cooling fan relays and coolant temperature switch and replace as necessary. If cooling fan relays and coolant temperature switch are okay, check for damaged connectors or an open circuit between cooling fan relay and coolant temperature switch.
  3. Reconnect coolant temperature switch. Warm engine to more than about 200°F (93°C). Cooling fans should operate at high speed. If cooling fans do not operate at high speed, replace coolant temperature sensor/switch. Cooling fan should also activate when A/C pressure switch indicates high A/C line pressure. See A/C PRESSURE SWITCH (LS400) under COOLING FAN .
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