Cooling Fan Controls Symptom Troubleshooting Index

Symptom
Diagnostic procedure
Also check for
Engine overheats
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Check the coolant level.
Check for the coolant leakage (from gaskets, hoses, O-rings, etc.).
Check for dirt, leaves, or insects on radiator and condenser.
Check for deteriorated coolant.
Check for damaged or deformed fan shroud.
Check for plugged or deteriorated radiator hoses.
Check for plugged heater core or hoses.
Check for a damaged cylinder head gasket.
With A/C: The A/C condenser fan runs at low speed, but it does not run at high speed when the engine coolant temperature is above 96.5 °C (206 °F)
Cleanliness and tightness of all connectors
With A/C: With the A/C off and the engine coolant temperature at 96.5 °C (206 °F) or below, the radiator fan runs at high speed and the A/C condenser fan does not run. When the engine coolant temperature is above 96.5 °C (206 °F), both fans run at high speed
  • If the relay is faulty, replace the circuit bard.
  • If the relay is OK, check for a short in the wire between the under-hood fuse/relay box terminal B11 and radiator fan motor 2P connector terminal No. 1.
Cleanliness and tightness of all connectors
With A/C: Both the radiator fan and the A/C condenser fan run at high speed with the ignition switch to ON (II), the A/C off, and the engine coolant temperature below 94.5 °C (202 °F)
Check for a short in the wire between the under-hood fuse/relay box terminal D10 and ECM/PCM connector terminal A5.
Cleanliness and tightness of all connectors
With A/C: Both the radiator fan and the A/C condenser fan run at low speed with the ignition switch to ON (II) and the A/C off
Check for a short in the wire between radiator fan relay 4P socket terminal No. 3 and ECM/PCM connector terminal A4.
Cleanliness and tightness of all connectors
With A/C: Both the radiator fan and the A/C condenser fan do not run at low speed with the A/C on
Cleanliness and tightness of all connectors
With A/C: Both the radiator fan and the A/C condenser fan run at low speed, but radiator fan does not run at high speed when the engine coolant temperature is above 96.5 °C (206 °F)
  • If the relay is faulty, replace the circuit board.
  • If the relay is OK, check for an open in the wire between the under-hood fuse/relay box terminal B1 and body ground.
  • Poor ground at G301
  • Cleanliness and tightness of all connectors
With A/C: Both the radiator fan and the A/C condenser fan do not run at high speed when the engine coolant temperature is above 96.5 °C (206 °F)
Check for an open in the wire between the under-hood fuse/relay box terminal D10 and ECM/PCM connector terminal A5.
Cleanliness and tightness of all connectors
Without A/C: The radiator fan does not run when the engine coolant temperature is above 96.5 °C (206 °F)
Cleanliness and tightness of all connectors