Radiator and A/C Condenser Fan Low Speed Circuit Troubleshooting
NOTE: Before doing any symptom troubleshooting, check for powertrain DTCs.
  1. Check the No. 18 (20 A) fuse in the under-hood fuse/relay box, and the No. 36 (10 A) fuse in the under-dash fuse/relay box.
Are the fuses OK?
YES -
Go to Step 2 .
NO -
Replace the fuses, and recheck. If fuses blow again, check for a short in the No. 18 (20 A) and No. 36 (20 A) fuses circuit.■
  1. Connect the HDS to the DLC.
  1. Turn the ignition switch ON (II).
  1. Turn on the A/C on the heater control unit.
  1. Check the FAN LOW CTRL in the PGM-FI Data List with the HDS.
Is the FAN LOW CTRL on?
YES -
Go to Step 6 .
NO -
Substitute a known-good ECM, and retest. If the symptom/indication goes away with a known-good ECM, replace the original ECM. ■
  1. Turn the ignition switch OFF.
  1. Jump the SCS line with the HDS.
    NOTE: This step must be done to protect the engine control module (ECM) from damage.
  1. Disconnect ECM connector A (44P).
  1. Turn the ignition switch ON (II).
  1. Measure the voltage between ECM connector A (44P) terminal No. 4 and body ground.
Is there battery voltage?
YES -
Go to Step 11 .
NO -
Repair open in the wires between the under-hood fuse/relay box and the ECM, or between the No. 36 (10 A) fuse in under-dash fuse/relay box and the under-hood fuse/relay box. If wires are OK, replace the under-hood fuse/relay box. ■
  1. Turn the ignition switch OFF.
  1. Connect the ECM connector A (44P) terminal No. 4 to body ground with a jumper wire.
  1. Turn the ignition switch ON (II).
Do the A/C condenser and radiator fans run on low?
YES -
Check for loose wires or poor connections at ECM connector A (44P) terminal No. 4. If the connections are good, substitute a known-good ECM, and recheck. If the symptom/indication goes away, replace the original ECM. ■
NO -
Go to Step 14 .
  1. Turn the ignition switch OFF.
  1. Disconnect the radiator fan 2P connector.
  1. Turn the ignition switch ON (II).
  1. Measure the voltage between the radiator fan 2P connector terminal No. 2 and body ground.
Is there battery voltage?
YES -
Go to Step 18 .
NO -
Repair open in the wire between the under-hood fuse/relay box and the radiator fan. If the wire is OK, replace the under-hood fuse/relay box. ■
  1. Turn the ignition switch OFF.
  1. Reconnect the radiator fan 2P connector.
  1. Connect the radiator fan 2P connector terminal No. 1 to body ground with a jumper wire.
  1. Turn the ignition switch ON (II).
Does the radiator fan run?
YES -
Go to Step 22 .
NO -
  1. Turn the ignition switch OFF.
  1. Disconnect the jumper wire from the radiator fan 2P connector.
Is the relay OK?
YES -
Go to Step 25 .
NO -
Replace the fan control relay.■
  1. Turn the ignition switch ON (II).
  1. Measure the voltage between the fan control relay 5P socket terminal No. 1 and body ground.
Is there battery voltage?
YES -
Go to Step 27 .
NO -
Repair open in the wire between the radiator fan and the fan control relay.■
  1. Turn the ignition switch OFF.
  1. Disconnect the jumper wire from ECM connector A (44P).
  1. Disconnect the A/C condenser fan 2P connector.
  1. Check for continuity between the fan control relay 5P socket terminal No. 4 and the A/C condenser fan 2P connector terminal No. 2.
Is there continuity?
YES -
Go to Step 31 .
NO -
Repair open in the wire between the fan control relay and the A/C condenser fan.■
  1. Check for continuity between the A/C condenser fan 2P connector terminal No. 1 and body ground.
Is there continuity?
YES -
NO -
Check for an open in the wire between the A/C condenser fan and body ground. If the wire is OK, check for poor ground at G301. ■