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Home >> Jeep >> 2006 >> Liberty Limited, 2.8 5 >> Repair and Diagnosis >> Engine Performance >> System >> Diesel - DTCS P0671 To P1102 >> Diagnosis And Testing >> P0683-Glow Plug Module Signal Circuit Malfunction >> Diagnostic Test

Diagnostic Test

  1. 1) CHECK FOR ACTIVE DTC 
    NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.
    NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.

    Turn the ignition on.

    With the scan tool, erase ECM DTCs.

    Perform several engine run cycles, turning the ignition off for at least 20 seconds between each engine run cycle.

    Turn the ignition on and wait at least 90 seconds.

    With the scan tool, read ECM DTCs.

    Did this DTC set again? 

    Yes 

    1. Go To  2).

    No 

    1. Refer to *INTERMITTENT DTC .
  2. 2) GLOW PLUG MODULE SIG/CONTROL CIRCUIT OPEN 

    Turn the ignition off.

    Disconnect the Glow Plug Module harness connectors.

    Disconnect the ECM harness connectors.

    Measure the resistance of the Glow Plug Module Signal circuit.

    Measure the resistance of the Glow Plug Module Control circuit.

    Is the resistance below 10.0 ohms for both measurements? 

    Yes 

    1. Go To  3).

    No 

    1. Repair the Glow Plug Module circuit(s) that measured above 10.0 ohms for an open.
    2. Perform ECM VERIFICATION TEST .
  3. 3) GLOW PLUG MODULE SIG/CONTROL CIRCUIT SHORTED TO GROUND 

    Turn the ignition off.

    Disconnect the Glow Plug Module harness connectors.

    Disconnect the ECM harness connectors.

    Measure the resistance between ground and the Glow Plug Module Signal circuit.

    Measure the resistance between ground and the Glow Plug Module Control circuit.

    Is the resistance above 1000 ohms for both measurements? 

    Yes 

    1. Go To  4).

    No 

    1. Repair the Glow Plug Module circuit(s) that measured below 1000 ohms for a short to ground.
    2. Perform ECM VERIFICATION TEST .
  4. 4) GLOW PLUG MODULE SIG/CONTROL CIRCUIT SHORTED TO VOLTAGE 

    Turn the ignition off.

    Disconnect the Glow Plug Module harness connectors.

    Disconnect the ECM harness connectors.

    Remove the ASD Relay.

    Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.

    Measure the voltage of the Glow Plug Module Signal circuit.

    Measure the voltage of the Glow Plug Module Control circuit.

    Is the voltage below 1.0 volt for both measurements? 

    Yes 

    1. Go To  5).

    No 

    1. Repair the Glow Plug Module circuit(s) that measured above 1.0 volt for a short to voltage.
    2. Perform ECM VERIFICATION TEST .
  5. 5) GLOW PLUG CONTROL MODULE 

    Turn the ignition off.

    Replace the Glow Plug Module in accordance with the Service Information.

    Reconnect all connectors.

    Turn the ignition on.

    With the scan tool, erase ECM DTCs.

    Perform several engine run cycles, turning the ignition off for at least 20 seconds between each engine run cycle.

    With the scan tool, read the ECM DTCs.

    Did this DTC set again? 

    Yes 

    1. Replace and program the Engine Control Module in accordance with the Service Information.
    2. Perform ECM VERIFICATION TEST .

    No 

    1. Test Complete.
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