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Cooling Fan Relay

NOTE: For cooling fan circuit identification, see Fig 1 or wiring diagram in WIRING DIAGRAM .
Fig 1: Identifying Cooling Fan Relay Circuits
G95H17597Courtesy of FORD MOTOR CO.

  1. 1) Code 1474: Check For VPWR To Cooling Fan Relay

    Code 1474 indicates that circuit failure has occurred on Fan Control (FC) circuit. Following are possible causes for this fault:
    • Open Or Shorted Circuit
    • Open VPWR Circuit To Cooling Fan Relay
    • Faulty Cooling Fan Relay
    • Faulty PCM

    Turn ignition off. Disconnect cooling fan relay. Relay is located in engine compartment fuse block. Turn ignition on. Measure voltage between negative battery terminal and VPWR circuit terminal at cooling fan relay wiring harness connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, locate and repair open VPWR circuit. Reconnect cooling fan relay and repeat QUICK TEST.

  2. 2) Check FC Circuit

    Turn ignition off. Connect NGS scan tester to Data Link Connector (DLC). Turn ignition on. Access Output Test Mode on NGS scan tester. Connect DVOM positive lead to VPWR circuit terminal of cooling fan relay wiring harness connector. Connect DVOM negative lead to FC circuit terminal of cooling fan relay wiring harness connector. Observe DVOM and turn cooling fan on and off several times. If voltage does not change more than 0.5 volt when cooling fan is turned from off to on, go to next step. If voltage changes more than 0.5 volt when cooling fan is turned from off to on, replace cooling fan relay. Repeat QUICK TEST.

  3. 3) Check For Short To Power In FC Circuit

    Turn ignition off. Disconnect cooling fan relay. Disconnect PCM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between negative battery terminal and FC circuit terminal at cooling fan relay wiring harness connector. If voltage is less than one volt, go to next step. If voltage is one volt or more, locate and repair short to power in FC circuit. Reconnect all components and repeat QUICK TEST.

  4. 4) Check For Short To Ground In FC Circuit

    Turn ignition off. Disconnect NGS scan tester from Data Link Connector (DLC), if applicable. Ensure cooling fan relay and PCM are disconnected. Install breakout box, leaving PCM disconnected. Measure resistance between test pin No. 28 and test pins No. 51, 103 (PWR GND), and 91 (SIG RTN) at breakout box. If all readings are more than 10,000 ohms, go to next step. If any reading is 10,000 ohms or less, locate and repair short to ground in appropriate circuit. Reconnect all components and repair QUICK TEST.

  5. 5) Check FC Circuit Continuity

    Measure resistance between test pin No. 28 at breakout box and FC circuit terminal at cooling fan relay wiring harness connector. If resistance is less than 5 ohms, replace PCM. Remove breakout box, reconnect all components and recheck system operation. If resistance is 5 ohms or more, locate and repair open FC circuit. Remove breakout box, reconnect all components and recheck system operation.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 10). No test procedures have been omitted.

  6. 10) Cooling Fan Inoperative

    Turn ignition off. Connect NGS scan tester to Data Link Connector (DLC). Turn ignition on. Access Output Test Mode on NGS scan tester. Disconnect cooling fan motor. Turn cooling fan on. Measure voltage between power-to-fan circuit terminal and ground circuit terminal at cooling fan wiring harness connector. If voltage is more than 10.5 volts, replace cooling fan motor and recheck system operation. If voltage is 10.5 volts or less, remain in Output Test Mode and go to next step.

  7. 11) Check Cooling Fan Ground Circuit

    Measure voltage between negative battery terminal and power-to-fan circuit at cooling fan relay wiring harness connector. If voltage is 10.5 volts or less, go to next step. If voltage is more than 10.5 volts, locate and repair open ground circuit to cooling fan motor. Reconnect all components and recheck system operation.

  8. 12) Check For B + To Cooling Fan Relay

    Turn ignition off. Disconnect cooling fan relay. Relay is located in engine compartment fuse block. Measure voltage between negative battery terminal and B + circuit terminal at cooling fan relay wiring harness connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, locate and repair open B + circuit to cooling fan relay. Reconnect all components and recheck system operation.

  9. 13) Check Power-To-Fan Circuit Continuity

    Measure resistance of power-to-fan circuit between cooling fan wiring harness connector and cooling fan relay wiring harness connector. If resistance is less than 5 ohms, replace cooling fan relay. Reconnect all components and recheck system operation. If resistance is 5 ohms or more, locate and repair open power-to-fan circuit between cooling fan motor and cooling fan relay.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.

  10. 20) Cooling Fan Always Runs

    Turn ignition off. Disconnect cooling fan relay. Turn ignition on. If fan is still on, locate and repair short to power in power-to-fan circuit. Reconnect all components and recheck system operation. If fan is off, replace cooling fan relay and recheck system operation.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 20) to step 30). No test procedures have been omitted.

  11. 30) Code 1474: Check For Intermittent Open Or Short To Ground

    Continuous Memory Code 1474 indicates a Fan Control (FC) circuit failure has occurred. Following are possible causes for this fault:
    • Open VPWR To Cooling Fan Relay
    • Open Coil In Cooling Fan Relay
    • Open Or Short In FC Circuit (PCM Terminal No. 28)

    Connect NGS scan tester to Data Link Connector (DLC). Turn ignition on. Using scan tester, access Low Fan Control Actual (LFCA) PID. Observe NGS scan tester for indication of fault while performing the following (LFCA PID will turn on to indicate fault):

    • Shake and bend Fan Control (FC) circuit between PCM terminal No. 28 and cooling fan relay.
    • Shake and bend VPWR circuit between EEC-V power relay and cooling fan relay.
    • Lightly tap on cooling fan relay to simulate road shock.

    If fault is indicated, isolate and repair open or short to ground in wiring harness. If fault is not indicated, go to next step.

  12. 31) Check Fan Control (FC) Circuit Intermittent

    Turn ignition on. Leave NGS scan tester connected to DLC with LFCA PID accessed. Disconnect cooling fan relay. LFCA PID should be on. Observe NGS scan tester for indication of fault while performing the following (LFCA PID will turn off to indicate a short to power):
    • Shake and bend Fan Control (FC) circuit between PCM terminal No. 28 and cooling fan relay.

    If a fault is indicated, locate and repair short to power in fan control circuit between PCM and cooling fan relay. If no fault is indicated, no problem is indicated at this time.

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