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Home >> Jeep >> 2018 >> Grand Cherokee Laredo, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 5 (3.0L Diesel - DTCS P0001-00 To P01CC-00) >> DTC Troubleshooting >> P0102-00-Mass Air Flow Sensor Circuit Low >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR AN ACTIVE DTC 
    1. Ignition on, engine not running.
    2. With the scan tool, record all freeze frame data and record any DTCs on the repair order.
    3. With the scan tool, erase DTCs in the Powertrain Control Module (PCM).
    4. Start the engine and allow it to reach normal operating temperature.
    5. With the scan tool, read DTCs and record on the repair order.

      Is the DTC active or pending?

      Yes 

      • Go To  2

      No 

  2. CHECK FOR OTHER DTCS 
    1. Refer to the recorded DTCs.

      Are there any 5-Volt Reference DTCs active or pending?

      Yes 

      • Perform the applicable diagnostic procedure(s). Refer to DTC INDEX .

      No 

      • Go To  3
  3. CHECK THE INTAKE AND EXHAUST SYSTEM FOR LEAKS OR RESTRICTIONS 
    1. Turn the ignition off.
    2. Inspect the exhaust system for damaged components that could cause exhaust flow blockage.
    3. Inspect all air intake, crankcase vent and turbocharger related hoses/tubes and connections for damage, air leaks or blockage.
    4. Inspect the Charge Air Cooler hoses/tubes and connections for damage, air leaks or blockage.
    5. Inspect the air filter for excessive dirt, soiling or other problems that may cause restricted air flow.

      Were any problems found?

      Yes 

      No 

      • Go To  4
  4. CHECK THE (K142) MAF SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    1. Measure the resistance between ground and the (K142) MAF Sensor Signal circuit at the MAF/Intake Air Sensor harness connector.

      Is the resistance above 10k Ohms?

      Yes 

      • Go To  5

      No 

      • Repair the (K142) Mass Air Flow Sensor Signal circuit for a short to ground.
      • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  5. CHECK THE (K142) MAF SENSOR SIGNAL CIRCUIT FOR A SHORT TO THE (K757) MAF SENSOR GROUND CIRCUIT 
    1. Measure the resistance between the (K142) MAF Sensor Signal circuit and the (K757) MAF Sensor Ground circuit at the MAF/Intake Air Sensor harness connector.

      Is the resistance above 10k Ohms?

      Yes 

      • Go To  6

      No 

      • Repair the (K142) Mass Air Flow Sensor Signal circuit for a short to the (K757) Mass Air Flow Sensor Ground circuit.
      • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. CHECK THE (F343) FUSED ASD RELAY OUTPUT CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the MAF harness connector.
    3. Turn the ignition on.
    4. Using a 12-volt test light connected to ground, probe the (F343) Fused ASD Relay Output circuit at the MAF 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 

      • Go To  7

      No 

      • Repair the (F343) Fused ASD/Main Relay Output circuit for an open or high resistance.
      • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  7. CHECK THE (Z909) GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Using a 12-volt test light connected to B+, probe the (Z909) Ground circuit at the MAF 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 

      • Go To  8

      No 

      • Repair the (Z909) MAF/Intake Air Sensor Main Ground circuit for an open or high resistance.
      • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  8. CHECK THE MAF/INTAKE AIR SENSOR FOR PROPER OPERATION 
    1. Reconnect the PCM C1 harness connector.
    2. Replace the Mass Air Flow/Intake Air Sensor in accordance with the service information. Refer to SENSOR, MASS AIRFLOW (MAF), REMOVAL .
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs.
    5. Start the engine and allow it to reach normal operating temperature.
    6. With the scan tool, select View DTCs.

      Is the status Active for this DTC?

      Yes 

      • Go To  9

      No 

  9. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all PCM harness connectors.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Check for spread terminals and verify proper terminal tension.

      Repair any conditions that are found.

    5. Connect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Connect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. With the scan tool, erase DTCs.
    9. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    10. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      No 

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