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Home >> Dodge and Ram >> 2003 >> Durango Base, 5.9 Z, 4WD, Part Time >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 5.9L >> Diagnostic Tests >> DTC P1491: Cooling Fan Control Relay Circuit >> Testing
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DTC P1491: Cooling Fan Control Relay Circuit: Testing

  1. Turn ignition on, with engine off. With the DRBIII® scan tool, read the DTCs and record the related freeze frame data. Is the DTC Specific Good Trip Counter displayed and equal to zero? If yes, go to next step. If no, see INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn the ignition off. Remove the radiator fan relay from the Power Distribution Center (PDC). Using a 12-volt test light connected to ground, probe the (A17) fused B+ circuit in the PDC. Does the test light illuminate brightly? If yes, go to next step. If no, repair the open in the (A17) fused B+ circuit. Inspect fuses and replace as necessary.
  3. Turn ignition on, with engine off. Using a 12-volt test light connected to ground, probe the (F18) fused ignition switch circuit in the PDC. Does the test light illuminate brightly? If yes, go to next step. If no, repair the open in the (F18) fused ignition switch circuit.
  4. Turn the ignition off. Disconnect the PCM harness connectors. Measure the resistance of the (C24) radiator fan relay control circuit from the PDC to PCM harness connector. Is the resistance less than 5.0 ohms? If yes, go to next step. If no, repair the open in the (C24) radiator fan relay control circuit.
  5. Measure the resistance between ground and the (C24) radiator fan relay control circuit. Is the resistance more 100 k/ohms? If yes, go to next step. If no, repair the short to ground in the (C24) radiator fan relay control circuit.
  6. Turn the ignition off. Reinstall the radiator fan relay. Connect a jumper wire to the radiator fan relay control circuit in the PCM harness connector. Momentarily connect the other end of the jumper wire to ground. Did the radiator fan actuate? If yes, go to next step. If no, replace the radiator fan relay.
    7. NOTE: Before continuing, disconnect the PCM harness connectors and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.
  7. Using the wiring diagram as a guide, inspect the wire harness and connectors. Visually inspect the related wire harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect both the component and the PCM connectors. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace and program the PCM. See PROGRAMMING .
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