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Home >> Jeep >> 2005 >> Wrangler X, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 627 (Powertrain Diagnostic Procedures - DRIVEABILITY - Gas - Symptom & Diagnostic Tests (DTCS P0031 To P1899)) >> DRIVEABILITY - Gas - Diagnostic Tests >> P1391-Intermittent Loss Of CMP Or CKP (Gas - Except NGC) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2004 Dodge Pickup and 2004 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Refer to VERIFICATION TESTS for appropriate verification test procedures.
  1. Ignition on, engine not running.
    WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.

    With the DRBIII®, read DTCs and record the related Freeze Frame data.

    Start the engine and run until operating temp is reached. (Closed Loop)

    If the DTC does not return right away it may be necessary to test drive the vehicle to duplicate the DTC.

    Does the P1391 return?

    1. Yes --> Go To 2
    2. No --> Refer to the SYMPTOM: INTERMITTENT CONDITION  Symptom (Diagnostic Procedure).

      Perform POWERTRAIN VERIFICATION TEST VER - 5 .

  2. Turn the ignition off.

    With the DRBIII® as a Dual Channel Lab Scope and Miller special tool #6801, backprobe the (K44) CMP Signal circuit in the CMP harness connector and PCM harness connector.

    WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.

    Start the engine.

    Observe the lab scope screen.

    Are there any irregular or missing signals?

    1. Yes --> Go To 3
    2. No --> Go To 6
  3. Turn the ignition off.

    Visually inspect the related wire harness. Look for any chafed, pierced, pinched, or partially broken wires.

    Visually inspect the related wire harness connectors. Look for broken, bent, pushed out, or corroded terminals.

    Ensure the Crankshaft Position Sensor and the Camshaft Position Sensor are properly installed and the mounting bolt(s) are torqued to specification.

    Refer to any TSB that may apply.

    Were any of the above conditions present?

    1. Yes --> Repair as necessary

      Perform POWERTRAIN VERIFICATION TEST VER - 5 .

    2. No --> Go To 4
  4. Remove the Camshaft Position Sensor.

    Inspect the Tone Wheel/Pulse Ring for damage, foreign material, or excessive movement.

    Were any problems found?

    1. Yes --> Repair or replace the Tone Wheel/Pulse Ring as necessary.

      Perform POWERTRAIN VERIFICATION TEST VER - 5 .

    2. No --> Go To 5
  5. If there are no possible causes remaining, view repair.
    1. Repair
      1. Replace the Camshaft Position Sensor.
      2. Perform POWERTRAIN VERIFICATION TEST VER - 5 .
  6. Turn the ignition off.

    With the DRBIII® as a Dual Channel Lab Scope and the Miller special tool #6801, backprobe the (K44) CMP Signal circuit in the PCM harness connector and in the CMP harness connector.

    WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.

    Start the engine.

    Carefully wiggle the related wire harness and gently tap on the CMP sensor.

    Observe the lab scope screen.

    Look for any differences in the two patterns generated by the CMP Sensor.

    If the Channel 1 and Channel 2 patterns are different, repair the wiring/connection concern

    Does the DRBIII® screen display any missing or irregular patterns?

    1. Yes --> Inspect the wire harness and connectors. If no problem is found replace Cam Position Sensor.

      Perform POWERTRAIN VERIFICATION TEST VER - 5 .

    2. No --> Go To 7
  7. Turn the ignition off.

    With the DRBIII® as a Dual Channel Lab Scope and the Miller special tool #6801, backprobe the (K24) CKP Signal circuit in the CKP harness connector and PCM harness connector.

    WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.

    Start the engine.

    Observe the lab scope screen.

    Are there any irregular or missing signals?

    1. Yes --> Go To 8
    2. No --> Go To 11
  8. Turn the ignition off.

    Visually inspect the related wire harness.

    Look for any chafed, pierced, pinched, or partially broken wires.

    Visually inspect the related wire harness connectors.

    Look for broken, bent, pushed out, or corroded terminals. Ensure the Crankshaft Position Sensor and the Camshaft Position Sensor are properly installed and the mounting bolt(s) are torqued to specification.

    Refer to any TSB that may apply.

    Were any of the above conditions present?

    1. Yes --> Repair as necessary

      Perform POWERTRAIN VERIFICATION TEST VER - 5 .

    2. No --> Go To 9
  9. Remove the Crankshaft Position Sensor.

    Inspect the Tone Wheel/Flex Plate slots for damage, foreign material, or excessive movement.

    Were any problems found?

    1. Yes --> Repair or replace the Tone Wheel/Flex Plate as necessary.

      Perform POWERTRAIN VERIFICATION TEST VER - 5 .

    2. No --> Go To 10
  10. If there are no possible causes remaining, view repair.
    1. Repair
      1. Replace the Crankshaft Position Sensor.
      2. Perform POWERTRAIN VERIFICATION TEST VER - 5 .
    11. NOTE: The conditions that set this DTC are not present at this time. The following test may help in identifying the intermittent condition.
    WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
  11. Turn the ignition off.

    With the DRBIII® as a Dual Channel Lab Scope and the Miller special tool #6801, backprobe the (K24) CKP Signal circuit in the PCM harness connector and CKP harness connector.

    Start the engine.

    Carefully wiggle the related wire harness and gently tap on the CKP sensor.

    Compare the Channel 1 reading to the Channel 2 reading on the lab scope screen.

    Both of the readings should be the same. Were any of the above conditions present?

    1. Yes --> Repair the wiring or connector concern.

      Perform POWERTRAIN VERIFICATION TEST VER - 5 .

    2. No --> Test Complete.
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