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Home >> Jeep >> 2007 >> Grand Cherokee Laredo, 3.0 M >> Repair and Diagnosis >> Engine Performance >> System >> Diesel - DTCS P0100 To P0197 >> P0100-Mass Air Flow Sensor >> Diagnostic Test

Diagnostic Test

  1. 1) DTC IS ACTIVE 

    Ignition on, engine not running.

    With the scan tool, Clear DTCs in the Engine Control Module (ECM).

    Start the engine and allow it to reach normal operating temperature.

    With the scan tool, select View DTCs.

    Is the status Active for this DTC? 

    Yes 

    1. Go to step  2).

    No 

    1. Refer to *CHECKING FOR AN INTERMITTENT CONDITION .
  2. 2) (K362) MASS AIR FLOW TEMPERATURE SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE 
    Fig 1: Checking Inlet Air Temperature Sensor Signal Circuit
    GC0039960Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the Mass Air Flow Sensor harness connector.

    Disconnect the Engine Control Module (ECM) harness connector.

    Remove the ASD Relay.

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

    Turn the ignition on.

    Measure the voltage of the (K362) Mass Air Flow Temperature Sensor Signal circuit in the Mass Air Flow Sensor harness connector.

    Is there any voltage present? 

    Yes 

    1. Repair the (K362) Mass Air Flow Temperature Sensor Signal circuit for a short to voltage.
    2. Perform ECM VERIFICATION TEST .

    No 

    1. Go to step  3).
  3. 3) (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE 
    Fig 2: Checking Mass Air Flow Sensor Signal Circuit Shorted To Voltage
    GC0039961Courtesy of CHRYSLER LLC
    NOTE: Jumper wire should still be in place.

    Measure the voltage of the (K157) Mass Air Flow Sensor Signal circuit in the Mass Air Flow Sensor harness connector.

    Is there any voltage present? 

    Yes 

    1. Repair the (K157) Mass Air Flow Sensor Signal circuit for a short to voltage.
    2. Perform ECM VERIFICATION TEST .

    No 

    1. Go to step  4).
  4. 4) (K957) MASS AIR FLOW SENSOR GROUND CIRCUIT SHORTED TO VOLTAGE 
    Fig 3: Checking Mass Air Flow Sensor Ground Circuit Shorted To Voltage
    GC0039962Courtesy of CHRYSLER LLC
    NOTE: Jumper wire should still be in place.

    Measure the voltage of the (K957) Mass Air Flow Sensor Ground circuit in the Mass Air Flow Sensor harness connector.

    Is there any voltage present? 

    Yes 

    1. Repair the (K957) Mass Air Flow Sensor Ground circuit for a short to voltage.
    2. Perform ECM VERIFICATION TEST .

    No 

    1. Go to step  5).
  5. 5) (F944) IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT OPEN OR HIGH RESISTANCE 
    Fig 4: Checking Fused Ignition Switch Output (Run-Start) Circuit
    GC0039963Courtesy of CHRYSLER LLC

    Using a 12 volt test light connected to ground, check the (F944) Ignition Switch Output (Run-Start) circuit in the Mass Air Flow Sensor harness connector.

    NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.

    Is the test light illuminated and bright? 

    Yes 

    1. Go to step  6).

    No 

    1. Repair the (F944) Ignition Switch Output (Run-Start) circuit for an open circuit of high resistance.
    2. Perform ECM VERIFICATION TEST .
  6. 6) (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT SHORTED TO THE (K362) MASS AIR FLOW TEMPERATURE SENSOR SIGNAL CIRCUIT 
    Fig 5: Checking Mass Air Flow Sensor Signal Circuit Shorted To Inlet Air Temperature Sensor Signal Circuit
    GC0039964Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Remove the jumper wire between cavity 30 and cavity 87 of the ASD Relay Connector.

    Measure the resistance between the (K157) Mass Air Flow Sensor Signal circuit and the (K362) Mass Air Flow Temperature Sensor Signal circuit in the Mass Air Flow Sensor harness connector.

    Is the resistance above 10.0 ohms? 

    Yes 

    1. Go to step  7).

    No 

    1. Repair the (K157) Mass Air Flow Sensor Signal circuit for a short to the (K362) Mass Air Flow Temperature Sensor Signal circuit.
    2. Perform ECM VERIFICATION TEST .
  7. 7) (K362) MASS AIR FLOW TEMPERATURE SENSOR SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE 
    Fig 6: Checking Inlet Air Temperature Sensor Signal Circuit
    GC0039965Courtesy of CHRYSLER LLC

    Measure the resistance of the (K362) Mass Air Flow Temperature Sensor Signal circuit between the Mass Air Flow Sensor harness connector and the Engine Control Module (ECM) harness connector.

    Is the resistance below 10.0 ohms? 

    Yes 

    1. Go to step  8).

    No 

    1. Repair the (K362) Mass Air Flow Temperature Sensor Signal circuit for an open circuit or high resistance.
    2. Perform ECM VERIFICATION TEST .
  8. 8) (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE 
    Fig 7: Checking Mass Air Flow Sensor Signal Circuit Open Or High Resistance
    GC0039966Courtesy of CHRYSLER LLC

    Measure the resistance of the (K157) Mass Air Flow Sensor Signal circuit between the Mass Air Flow Sensor harness connector and the Engine Control Module (ECM) harness connector.

    Is the resistance below 10.0 ohms? 

    Yes 

    1. Go to step  9).

    No 

    1. Repair the (K157) Mass Air Flow Sensor Signal circuit for an open circuit or high resistance.
    2. Perform ECM VERIFICATION TEST .
  9. 9) (K957) MASS AIR FLOW SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE 
    Fig 8: Checking Mass Air Flow Sensor Ground Circuit Open Or High Resistance
    GC0039967Courtesy of CHRYSLER LLC

    Measure the resistance of the (K957) Mass Air Flow Sensor Ground circuit between the Mass Air Flow Sensor harness connector and the Engine Control Module (ECM) harness connector.

    Is the resistance below 10.0 ohms? 

    Yes 

    1. Go to step  10).

    No 

    1. Repair the (K957) Mass Air Flow Sensor Ground circuit for an open circuit or high resistance.
    2. Perform ECM VERIFICATION TEST .
  10. 10) (K362) MASS AIR FLOW TEMPERATURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND 
    Fig 9: Checking Inlet Air Temperature Sensor Signal Circuit
    GC0039968Courtesy of CHRYSLER LLC

    Measure the resistance between ground and the (K362) Mass Air Flow Temperature Sensor Signal circuit in the Mass Air Flow Sensor harness connector.

    Is the resistance above 1000 ohms? 

    Yes 

    1. Go to step  11).

    No 

    1. Repair the (K362) Mass Air Flow Temperature Sensor Signal circuit for a short to ground.
    2. Perform ECM VERIFICATION TEST .
  11. 11) (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT SHORTED TO GROUND 
    Fig 10: Checking Mass Air Flow Sensor Signal Circuit Shorted To Ground
    GC0039969Courtesy of CHRYSLER LLC

    Measure the resistance between ground and the (K157) Mass Air Flow Sensor Signal circuit in the Mass Air Flow Sensor harness connector.

    Is the resistance above 1000 ohms? 

    Yes 

    1. Go to step  12).

    No 

    1. Repair the (K157) Mass Air Flow Sensor Signal circuit for a short to ground.
    2. Perform ECM VERIFICATION TEST .
  12. 12) (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT SHORTED TO THE (K957) MASS AIR FLOW SENSOR GROUND CIRCUIT 
    Fig 11: Checking Mass Air Flow Sensor Signal Circuit Shorted To Mass Air Flow Sensor Ground Circuit
    GC0039970Courtesy of CHRYSLER LLC

    Measure the resistance between the (K157) Mass Air Flow Sensor Signal circuit and the (K957) Mass Air Flow Sensor Ground circuit in the Mass Air Flow Sensor harness connector.

    Is the resistance above 1000 ohms? 

    Yes 

    1. Go to step  13).

    No 

    1. Repair the (K157) Mass Air Flow Sensor Signal circuit for a short to the (K957) Mass Air Flow Sensor Ground circuit.
    2. Perform ECM VERIFICATION TEST .
  13. 13) MASS AIR FLOW SENSOR 

    Connect the Engine Control Module (ECM) harness connector.

    Replace the Mass Air Flow Sensor in accordance with the Service Information

    Turn the ignition on.

    With the scan tool, Clear DTCs.

    Start the engine and allow it to reach normal operating temperature.

    With the scan tool, select View DTCs.

    Is the status Active for this DTC? 

    Yes 

    1. Go to step  14).

    No 

    1. Test Complete.
    2. Perform ECM VERIFICATION TEST .
  14. 14) ENGINE CONTROL MODULE (ECM) 

    Using the wiring diagram/schematic as a guide, inspect the wiring and connectors the Mass Air Flow Sensor and the Engine Control Module (ECM).

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

    Look for broken, bent, pushed out or corroded terminals.

    Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.

    Look for the data to change or for the DTC to reset during the wiggle test.

    Refer to any Technical Service Bulletins that may apply.

    Were any problems found? 

    Yes 

    1. Repair as necessary.
    2. Perform ECM VERIFICATION TEST .

    No 

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