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Home >> Jeep >> 2014 >> Wrangler Sahara, Standard Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 171 (2.4L - DTCS P1621 To U1418) >> DTC Troubleshooting >> P2174-Low Airflow/Restriction Detected (Instantaneous Accumulation) >> Diagnostic Test.

Diagnostic Test.

WARNING: This page is about a different car, the 2016 Dodge Journey and 2015 Dodge Journey. However, it is still accessible from the selected car via links, so may be relevant.
  1. ACTIVE DTC 
    NOTE:

    Diagnose and repair any TP Sensor or MAP Sensor DTCs before continuing.

    NOTE:

    Diagnose and repair any VSS or 5 Volt supply circuit DTCs before continuing.

    NOTE:

    The throttle plate and linkage should be free from binding and carbon build up.

    NOTE:

    Make sure the throttle plate is at the idle position.

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

      When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

    2. With the scan tool, select View DTCs.

      Is the status Active for this DTC?

      Yes 

      • Go To  2

      No 

  2. VACUUM LEAK 
    1. Inspect the intake manifold, power brake booster, and PCV system for any vacuum leaks.
    2. Inspect the throttle plate. If the throttle blade is bent or will not close, the throttle body may need to be replaced.
    3. Inspect the MAP Sensor and Throttle Body for proper installation.
    4. Inspect the air intake system for any restrictions or obstructions.
    5. Inspect the engine for any mechanical conditions that can cause low engine vacuum.

      Were any problems found?

      Yes 

      No 

      • Go To  3
  3. MAP SENSOR OPERATION 
    1. Start the engine.
    2. With a scan tool, monitor the MAP Sensor voltage.
    3. Snap the throttle.

      Does the MAP Sensor voltage vary from below 2.0 volts at idle to above 3.5 volts at wide open throttle?

      Yes 

      • Go To  5

      No 

      • Go To  4
  4. MAP SENSOR 
    1. Turn the ignition off.
    2. Disconnect the MAP Sensor harness connector.
    3. Disconnect the PCM harness connector.
    4. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the MAP Sensor and the Powertrain Control Module (PCM).
    5. Look for any chafed, pierced, pinched, or partially broken wires.
    6. Look for broken, bent, pushed out or corroded terminals.
    7. Check each of the MAP Sensor circuits for high resistance or a shorted condition.

      Were any problems found?

      Yes 

      No 

  5. THROTTLE FOLLOWER TEST 
    1. Ignition on, engine not running.
    2. With a scan tool, perform the Throttle Follower Test. and monitor the TP Sensor 1 and TP Sensor 2 voltages.
    3. Slowly press the throttle pedal down.
    4. The voltage for TP Sensor 1 should start at approximately 0.5 volts and increase to approximately 3.3 volts.
    5. The voltage for TP Sensor 2 should start at approximately 4.4 volts and decrease to approximately 1.7 volts.

      Is the voltage within the range specified for each sensor?

      Yes 

      • Go To  7

      No 

      • Go To  6
  6. THROTTLE BODY 
    1. Turn the ignition off.
    2. Disconnect the Throttle Body harness connector.
    3. Disconnect the PCM harness connector.
    4. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body and the Powertrain Control Module (PCM).
    5. Look for any chafed, pierced, pinched, or partially broken wires.
    6. Look for broken, bent, pushed out or corroded terminals.
    7. Check each of the Throttle Body circuits for high resistance or a shorted condition.

      Were any problems found?

      Yes 

      No 

      • Replace the Throttle Body in accordance with the Service Information.
      • Perform the PCM VERIFICATION Test. Refer to POWERTRAIN VERIFICATION TEST . .
  7. POWERTRAIN CONTROL MODULE (PCM) 
    1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body and the Powertrain Control Module (PCM) and between the MAP Sensor and the Powertrain Control Module (PCM).
    2. Look for any chafed, pierced, pinched, or partially broken wires.
    3. Look for broken, bent, pushed out or corroded terminals.
    4. Perform any Technical Service Bulletins that may apply.

      Were any problems found?

      Yes 

      No 

      • Replace and program the Powertrain Control Module (PCM) in accordance with the service information.
      • Perform the PCM VERIFICATION Test. Refer to POWERTRAIN VERIFICATION TEST . .
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