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Home >> Ford >> 1997 >> Mustang Base, 2D Convertible, Automatic >> Repair and Diagnosis >> Engine Mechanical >> Engine Cooling Fan - EEC-V >> Testing >> Variable Control Relay Module (VCRM) >> Diagnostic Aids

Diagnostic Aids

Perform this test only when instructed. This test is only intended to diagnose the following:

  1. 1) DTC P1484: Attempt To Regenerate DTC

    DTC P1484 indicates an open VCRM PWR GND circuit (terminal No. 1). Possible causes are an open VCRM PWR GND circuit or faulty VCRM. Clear DTCs. Start engine, turn A/C on and wait 15 seconds. Turn A/C and engine off, ignition on. Check for continuous memory DTCs. If Continuous memory DTC P1484 is present (hard code), go to next step. If Continuous memory DTC P1484 is not present (intermittent), go to step 4).

  2. 2) Check VCRM PWR GND Circuit Resistance

    Turn ignition off. Disconnect VCRM harness connector. Check for corroded, damaged or backed-out terminal pins. Repair as necessary. Using an ohmmeter, check resistance between negative battery terminal and terminal No. 1 at VCRM harness connector. If resistance is less than 5 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is not as specified, locate and repair open in VCRM PWR GND circuit. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 2) to step 4). No test procedures have been omitted.

  3. 4) Check VCRM PWR GND For Intermittent Open

    Turn ignition off. Visually check VCRM PWR GND circuit between VCRM terminal No. 1 and ground junction. Ground junction is located on left side of radiator support, near battery ground. Disconnect VCRM harness connector. Check for corroded, damaged or backed-out terminal pins. Repair as necessary. Connect a test light between VCRM terminals No. 1 and 15. Test light should be on. Observe test light for indication of fault (test light will turn off to indicate fault) while performing the following:
    • Shake and bend VCRM PWR GND circuit (Black wire) between VCRM and ground junction.

    If fault is indicated, isolate and repair open in PWR GND circuit. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If fault is not indicated, problem may be intermittent. Go to CIRCUIT TEST Z. See G - TESTS W/ CODES - 3.8L or G - TESTS W/ CODES - 4.6L article in ENGINE PERFORMANCE section.

    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.

  4. 10) DTC P1483: Attempt To Regenerate DTC

    DTC P1483 indicates that when cooling fan was activated, Power-To-Cooling Fan circuit exceeded normal current draw. This could be due to a hard fault or an intermittent condition. Possible causes are:
    • Short to ground in Power-To-Cooling Fan circuit.
    • Faulty cooling fan motor.
    • Faulty VCRM.

    Clear DTCs. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Check for continuous memory DTCs. If continuous memory DTC P1483 is present, go to next step. If continuous memory DTC P1483 is not present (intermittent), go to step 14).

  5. 11) Check Cooling Fan Motor

    Clear continuous memory. Disconnect cooling fan motor harness connector. Start engine. Turn A/C on and wait 15 seconds (but no longer than 20 seconds). Turn A/C and ignition off. Check for continuous memory DTCs. If continuous memory DTC P1483 is present, go to next step. Ignore any other DTCs at this time. If continuous memory DTC P1483 is not present, replace cooling fan motor. Reconnect all connectors. Repeat QUICK TEST.

  6. 12) Check For Short To Ground In Power-To-Cooling Fan Circuit

    Turn ignition off. Ensure cooling fan motor harness connector is disconnected. Disconnect VCRM harness connector. Check for corroded, damaged or backed-out terminal pins. Repair as necessary. Using an ohmmeter, check resistance of Light Blue wire between cooling fan motor harness connector and negative battery terminal. If resistance is greater than 10 k/ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is not as specified, locate and repair short to ground in Light Blue wire. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 14). No test procedures have been omitted.

  7. 14) Check For Intermittent Short To Ground In Cooling Fan Circuit

    Turn ignition off. Visually inspect Power-To-Cooling Fan circuit between terminal No. 2 of VCRM harness connector and cooling fan motor harness connector. Repair wiring as necessary. Connect a test light between VCRM terminals No. 2 and 4. Test light should be on, but not at full brightness. Observe test light for indication of fault (test light will get brighter to indicate fault) while performing the following:
    • Shake, wiggle and bend Power-To-Cooling Fan circuit (Light Blue wire) near cooling fan motor.

    Disconnect cooling fan motor harness connector. Test light should now be off. Again, observe test light for indication of fault (test light will turn on to indicate fault) while performing the following:

    • Shake, wiggle and bend Power-To-Cooling Fan circuit (Light Blue wire) between VCRM and cooling fan motor harness connector.

    If a fault is indicated, isolate fault and repair as necessary. Reconnect all components. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If no fault is indicated, problem may be intermittent. Go to CIRCUIT TEST Z. See G - TESTS W/ CODES - 3.8L or G - TESTS W/ CODES - 4.6L article in ENGINE PERFORMANCE section.

    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 20). No test procedures have been omitted.

  8. 20) DTC P1473: Verify Cooling Fan Is Not Always On Key On Engine Off (KOEO)

    DTC P1473 indicates an open or short to power in Power-To-Cooling Fan circuit. Possible causes are:
    • Open or short to power in Power-To-Cooling Fan circuit.
    • Open cooling fan motor ground circuit.
    • Open circuit in cooling fan motor.
    • Faulty VCRM.
    NOTE: Ensure cooling fan was not turning during KOEO self-test. If fan was turning, feedback voltage could be sent to VCRM through Power-To-Cooling Fan circuit, resulting in an invalid KOEO DTC P1473.

    Ensure engine is cooled off (cooling fan off). Turn A/C and defroster off. Turn ignition on. If cooling fan is on, go to step 25). If cooling fan is off, go to next step.

  9. 21) Check Cooling Fan Ground Circuit

    Turn ignition off. Disconnect cooling fan motor harness connector. Using an ohmmeter, check resistance between ground and cooling fan ground circuit at cooling fan motor harness connector. If resistance is less than 5 ohms, go to next step. If resistance is not as specified, locate and repair open in cooling fan ground circuit. Reconnect all components and repeat QUICK TEST.

  10. 22) Check Power-To-Cooling Fan Circuit

    Turn ignition off. Disconnect VCRM harness connector. Check for corroded, damaged or backed-out terminal pins. Repair as necessary. Using an ohmmeter, check resistance between Power-To-Cooling Fan circuit at cooling fan motor harness connector and terminals No. 2 and 3 at VCRM harness connector. If both readings are less than 5 ohms, go to next step. If either readings are not as specified, locate and repair open in Light Blue wire between VCRM and cooling fan motor harness connectors. Reconnect all components and repeat QUICK TEST.

  11. 23) Check Cooling Fan

    Turn ignition off. Ensure cooling fan is disconnected. Using an ohmmeter, check resistance between ground circuit (Black wire) and Power-To-Cooling Fan circuit (Light Blue wire) at cooling fan motor harness connector. If resistance is less than 10 ohms, replace VCRM. Reconnect all components and repeat QUICK TEST. If resistance is not as specified, replace cooling fan motor. Reconnect all components and repeat QUICK TEST.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 23) to step 25). No test procedures have been omitted.

  12. 25) Check For Short To Power

    Turn ignition off. Disconnect cooling fan motor harness connector. Disconnect VCRM harness connector. Check for corroded, damaged or backed-out terminal pins. Repair as necessary. Turn ignition on. Using a voltmeter, check voltage between ground and Power-To-Cooling Fan circuit (Light Blue wire) at cooling fan motor harness connector. If reading is less than one volt, replace VCRM. Reconnect all components and repeat QUICK TEST. If reading is not as specified, locate and repair short to power in Light Blue wire. Reconnect all components and repeat QUICK TEST.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 60). No test procedures have been omitted.

  13. 60) KOEO/KOER DTC P1625 &/Or DTC P1626

    DTC P1625 indicates that B + to VCRM fan circuit is not detected. DTC P1626 indicates that B + to VCRM A/C circuit is not detected. Testing for both DTCs are the same. Possible causes are:
    • Open B + circuit to VCRM terminals No. 4 and 5.
    • Faulty VCRM.

    Turn ignition off. Disconnect VCRM harness connector. Check for corroded, damaged or backed-out terminal pins. Repair as necessary. Using a voltmeter, check voltage between negative battery terminal and terminals No. 4 and 5 at VCRM harness connector. If both readings are greater than 10.5 volts, replace VCRM. Reconnect all components and repeat QUICK TEST. If either reading is not as specified, check cooling fan related fuses. If fuses are okay, locate and repair open in B + circuit. If fuse is blown, locate and repair short to ground in B + circuit. Reconnect all components and repeat QUICK TEST.

    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 60) to step 65). No test procedures have been omitted.

  14. 65) Continuous Memory DTC P1625 &/Or DTC P1626

    Continuous memory DTC P1625 indicates that an open B (+) supply to VCRM fan circuit has been detected. Continuous memory DTC P1626 indicates that an open B + supply to VCRM A/C circuit has been detected. Testing for both DTCs are the same. Possible cause is:
    • Intermittent open B + circuit to VCRM terminals No. 4 and 5.

    Turn ignition off. Disconnect VCRM harness connector. Check for corroded, damaged or backed-out terminal pins. Repair as necessary. Connect a test light between ground and terminal No. 5 at VCRM harness connector. Test light should be on. Observe test light for indication of fault (test light will turn off to indicate fault) while performing the following:

    • Shake, wiggle and bend B + circuit (Yellow wire) to VCRM terminals No. 4 and 5.
    • Lightly tap on cooling fan related fuses. Remove cooling fan related fuses and check for corrosion and damaged pins.

    Reinstall fuses. If a fault is indicated, isolate fault and repair as necessary. Reconnect all components and repeat QUICK TEST. If no fault is indicated, problem may be intermittent. Go to CIRCUIT TEST Z. See G - TESTS W/ CODES - 3.8L or G - TESTS W/ CODES - 4.6L article in ENGINE PERFORMANCE section.

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