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Test HY: Generator/Regulator System: Testing

NOTE: Proceed to DTC testing steps listed in FAULT CODE SETTING CONDITION  table of fault code setting condition.
FAULT CODE SETTING CONDITION

Fault Code KOEO KOER Continuous Memory
P0622    HY1  HY1
P1244    HY1  HY1
P1245    HY1  HY1
P1246    HY1  HY1
    NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  1. 1) For KOER & Continuous Memory Only DTCs P0622, P1244, P1245 & P1246: Verify Generator Drive Function
    The PCM monitors generator load from the generator/regulator in the form of frequency. The frequency range is determined by the temperature of the voltage regulator where 97 percent represents full load, below 6 percent means no load. Possible causes are:
    • Generator circuit short to GND.
    • Generator circuit short to PWR.
    • Generator circuit open.
    • Generator drive mechanism.
    • Damaged generator/regulator assembly.
    • Damaged PCM.

    Check generator drive belt condition and tension. Start engine and verify generator is turning. Repair as necessary. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. If no faults are found, go to step  3) (for Expedition, Explorer, Mountaineer and Navigator) or go to next step (all others).

  2. 2) Verify Charging System Is EEC Controlled

    Turn ignition switch to OFF position. Disconnect negative, then positive battery cable. Disconnect generator connector. Using a DVOM, measure resistance between BATT-SENSE and GEN-COM circuits at generator connector (except LS and Thunderbird). For LS and Thunderbird, measure resistance between GEN-MON and ground. See Figure-Figure . If resistance is 950-1050 ohms (except LS and Thunderbird) or 53-203 ohms (LS and Thunderbird), go to next step. If resistance is not as specified, replace generator/regulator assembly.

  3. 3) Check Battery Sense Voltage At Battery

    Reconnect generator connector. Reconnect battery cables to battery. Using a DVOM, measure voltage between battery terminals. Note voltage measurement. Using a DVOM, measure voltage between negative battery terminal and BATT-SENSE circuit at generator harness connector. If voltage is within .5 volt (plus or minus) of battery voltage measurement, go to next step (for Expedition, Explorer, Mountaineer and Navigator), or go to step  5) (all others). If voltage is not within .5 volt of battery voltage measurement, repair BATT-SENSE circuit as necessary.

  4. 4) Check EEC Control Circuit In PCM

    Turn ignition switch to OFF position. Disconnect generator and PCM harness connectors. Measure resistance between the I-Line and VPWR through the PCM where applicable for Expedition/Navigator. Measure resistance between the I-Line and ground through the PCM where applicable for Explorer/Mountaineer. If the resistances are within the ranges in the table, go to next step. See RESISTANCE VALUES FOR PCM CIRCUITS  table. If the resistances are not within the ranges in the table, replace PCM.
    RESISTANCE VALUES FOR PCM CIRCUITS

    Vehicle Range (Ohms)
    Expedition & Navigator 1550-1650
    Explorer & Mountaineer 100-150

  5. 5) Check GEN-MON & GEN-COM Circuits For Short To PWR

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Disconnect generator connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and GEN-COM and GEN-MON circuits at PCM harness connector. See Figure-Figure . If both voltage measurements are .5 volt or less, go to next step. If either voltage measurement is more than .5 volt, repair short to PWR in affected circuit.

  6. 6) Check GEN-COM & GEN-MON Circuits For Short To GND

    Turn ignition switch to OFF position. Using a DVOM, measure resistance between negative battery terminal and GEN-COM and GEN-MON circuits at PCM harness connector. If both resistance measurements are more than 10 k/ohms, go to next step. If either resistance measurement is 10 k/ohms or less, repair short to GND in affected circuit.

  7. 7) Check GEN-COM & GEN-MON Circuits For Open

    Using a DVOM, measure resistance of GEN-COM and GEN-MON circuits between PCM harness connector and generator harness connector. If both resistance measurements are less than 5 ohms, go to next step. If either resistance measurement is 5 ohms or more, repair open in affected circuit.

  8. 8) Check GEN-MON Signal

    Reconnect all connectors. Start engine and allow to idle. Using scan tool, access GFS PID from PID/DATA MONITOR & RECORD menu. If GFS PID (duty cycle) is 3-95 percent (for LS and Thunderbird) or 6-98 percent (all others), go to next step. If GFS PID (duty cycle) is not as specified, replace generator/regulator assembly.

  9. 9) Check GEN-COM Signal

    With engine idling, access ARC (Expedition & Navigator) or GENFDC (all others) PID from PID/DATA MONITOR & RECORD menu. Observe ARC or GENFDC PID value, while cycling headlights on and off. If ARC or GENFDC PID duty cycle reading switched within zero to 99 percent, fault is unable to be duplicated at this time. Go to TEST Z, step 1) . If ARC or GENFDC PID duty cycle reading did not switch within zero to 99 percent, replace PCM.
    10. NOTE: Explorer/Mountaineer do not have diagnostic PIDS, and LS/Thunderbird does not have a GENFDC PID.

  10. 10) Check Generator Charging Voltage
    Start engine and allow to idle. Using DVOM, measure battery voltage. If the battery voltage is 12.2-14.7 volts, go to TEST Z, step 1) . If the battery voltage is not 12.2-14.7 volts, replace generator/regulator assembly.
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