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  • P0647 High Voltage Detected At The A/C Clutch Relay

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    Mopar1973Man

    P0647 HIGH VOLTAGE DETECTED AT THE A/C CLUTCH RELAY

    When Monitored and Set Condition:

    When Monitored: When the ignition is on.
    Set Condition: When the signal from the A/C Clutch output does not match the signal from the A/C Clutch
    feedback.

    POSSIBLE CAUSES

    • LOOSE CONNECTION
    • FUSED BATTERY SUPPLY
    • A/C CLUTCH RELAY
    • INTERMITTENT CONDITION
    • ECM

    DIAGNOSTIC PROCEDURE

    1. Ignition on, engine not running. With the DRBIII®, actuate the A/C clutch relay. Can you hear the Relay clicking?
      Yes --> Go To 2
      No --> Go To 3
    2. Actuation still running. While the relay is clicking, wiggle the wiring harness and connectors throughout the circuit. Does this interrupt the clicking?
      Yes --> Repair the loose connection. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
      No --> Go To 3
    3. Ignition on, engine not running. Measure the voltage on the Fused Battery Supply circuit in the PDC. Is the voltage within 1 volt of battery voltage?
      Yes --> Go To 4
      No --> Repair the open Fused battery supply. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
    4. Remove the A/C Clutch Relay from the PDC.
      NOTE: Check connectors - Clean/repair as necessary.
      Measure the resistance between terminals 85 and 86 of the A/C Clutch Relay. Is the resistance less than 10 Ohms?
      Yes --> Go To 5
      No --> Replace the A/C clutch relay. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
    5. Reconnect the ECM harness connectors. Reinstall the A/C clutch relay. With the DRBIII®, actuate the A/C clutch relay. Turn the ignition on. While monitoring with the DRBIII®, disconnect the A/C Clutch Relay from the PDC. Did DTC P0646 set?
      Yes --> Refer to the SYMPTOM: INTERMITTENT CONDITION Symptom (Diagnostic Procedure). Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
      No --> Replace the ECM. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).


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