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Cooling Fan Runs Constantly

  1. Locate low-speed cooling fan relay No. 1 and high-speed cooling fan relay No. 2 (A/T) or cooling fan relay (M/T). Turn ignition on. Measure voltage on Black/Red wire at relay connector. If voltage is greater than 10 volts, go to step 2). If voltage is less than 10 volts, repair Black/Red wire to relay.
  2. Measure voltage on Black/White wire at relay connector. If voltage is more than 10 volts, go to step 3). If voltage is less than 10 volts, repair Black/White wire to relay.
  3. Turn ignition on. Ground Black/Green wire terminal at cooling fan relay (M/T) or at low-speed fan relay No. 1 (A/T) connector. Measure voltage at Blue/Yellow wire at relay connector. Remeasure voltage with Black/Green wire terminal not grounded. If voltage is less than 1.5 volts with Black/Green wire terminal not grounded and greater than 10 volts with Black/Green wire terminal grounded, go to step 4) for A/T models or step 7) for M/T models. If voltage is not as specified, replace relay in question.
  4. On A/T models, ground Blue/Red wire at relay terminal. Measure voltage (ignition on) on Blue/Black wire at cooling fan relay No. 2 (high speed). Remeasure voltage with Blue/Red wire not grounded. If voltage is less than 1.5 volts with Blue/Red wire terminal not grounded and more than 10 volts with Blue/Red wire terminal grounded, go to step 5). If voltage is not as specified, replace cooling fan relay No. 2 (high-speed).
  5. Turn ignition off. Measure resistance on Blue/Yellow wire between cooling relay (high-speed) and cooling fan resistor. If resistance is less than 5 ohms, go to step 6). If resistance is more than 5 ohms, repair Blue/Yellow wire.
  6. Measure resistance on Blue/Black wire between cooling fan resistor and cooling fan relay (high-speed). If resistance is less than 5 ohms, go to step 8). If resistance is more than 5 ohms, repair Blue/Black wire.
  7. On M/T models, measure resistance (ignition off) of Blue/Yellow wire between cooling fan relay and cooling fan motor. If resistance is less than 5 ohms, go to step 8). If resistance is more than 5 ohms, repair Blue/Yellow wire.
  8. On all models, measure resistance of Black wire between cooling fan motor and ground with ignition off. If resistance is less than 5 ohms, go to step 9). If resistance is more than 5 ohms, repair Black wire.
  9. Using a fused jumper, apply battery voltage to Blue/Black wire terminal at cooling fan motor. If cooling fan motor does not run, replace defective cooling fan motor. If cooling fan motor runs, go to step 10) for A/T models or step 11) for M/T models.
  10. On A/T models, apply battery voltage to Blue/Yellow wire terminal at fan motor resistor. If cooling fan motor runs, go to step 11). If cooling fan motor does not run, replace cooling fan motor resistor.
  11. On all models, turn ignition off. Measure resistance at Black/Green wire between ECU, test connector, radiator temperature switch and low-speed cooling fan relay (A/T) or condenser fan relay (M/T). If resistances are less than 5 ohms, go to step 12) for A/T models or step 13) for M/T models. If resistances are more than 5 ohms, repair affected wire.
  12. On A/T models, measure resistance at Black/Red wire between cooling fan relay No. 2 (high-speed) and ECU, condenser fan relay, test connector and high-speed radiator temperature switch. If resistances are less than 5 ohms, go to step 14). If resistances are more than 5 ohms, repair affected wire.
  13. On M/T models, turn ignition on. Ground cooling fan motor test connector. Cooling fan motor should run. If cooling fan motor does not run, replace radiator temperature switch.
  14. On A/T models, turn ignition on. Ground Black/Green wire terminal on cooling fan motor test connector. Cooling fan should run. If cooling fan does not run, replace low-speed radiator temperature switch. Ground Blue/Red wire terminal on test connector. Cooling fan should run. If cooling fan does not run, replace high-speed radiator temperature switch.
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