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Home >> Jeep >> 2021 >> Cherokee Trailhawk >> Repair and Diagnosis >> Engine Performance >> System >> 3.2L - DTCS P0300 To P054A >> DTC Troubleshooting >> P050B-Cold Start Ignition Timing Performance >> Diagnostic Test
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Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    1. Turn the ignition on.
      NOTE:

      Low battery voltage can also cause excessive current draw, in very hot and very cold ambient temperatures. Make sure the battery can pass a load test before continuing.

    2. Start the engine.
    3. Allow the engine to reach normal operating temperature.
    4. With a scan tool, read DTCs.
      NOTE:

      It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.

      Is the DTC active or pending?

      Yes 

      • Go To  2

      No 

  2. PERFORM A VISUAL INSPECTION OF THE THROTTLE PLATE FOR FOREIGN MATERIAL, SCORING, OR OTHER DAMAGE CAUSING THE THROTTLE PLATE TO STICK 
    1. Turn the ignition off.
    2. Remove the Air Cleaner Assembly from the Throttle Body.
    3. Check for any signs of a foreign material (ice, dirt, or excessive carbon build up) on the Throttle Plate or in the bore causing the Throttle Plate to stick.

      Were any signs of foreign material or scoring of the throttle plate or bore found?

      Yes 

      • Remove the debris if possible or replace the Throttle Body Assembly. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECK FOR A DIRTY AIR FILTER 
    1. Remove and inspect the Air Filter.

      Is the Air Filter dirty?

      Yes 

      No 

      • Go To  4
  4. CHECK THE FUEL SYSTEM FOR CONTAMINATION 
    1. Inspect the Fuel for contamination. (Dirt, water, or other foreign material)

      Is the fuel contaminated?

      Yes 

      No 

      • Go To  5
  5. CHECK THE (K447) ETC MOTOR (+) CIRCUIT FOR EXCESSIVE RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the PCM C2 harness connector.
      CAUTION:

      Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.

    3. Connect the (special tool #10436, Adapter, GPEC Diagnostic) in line with the PCM C2 harness connector.
    4. Using a Voltmeter perform a voltage drop test. Back probe the (K447) ETC Motor (+) circuit at the Throttle Body harness connector and GPEC Adaptor. Make sure the Voltmeter leads are connected so a positive polarity is displayed on the Voltmeter.
      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.

    5. Start the engine and allow it to reach normal operating temperature.
    6. Monitor the Voltmeter.

      Is the voltage below 0.2 volt?

      Yes 

      • Go To  6

      No 

      • Repair the excessive resistance in the (K447) ETC Motor (+) circuit.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. CHECK THE (K448) ETC MOTOR (-) CIRCUIT FOR EXCESSIVE RESISTANCE 
    1. Turn the ignition off.
    2. Move the Voltmeter leads to back probe the (K448) ETC Motor (-) circuit at the Throttle Body harness connector and the GPEC Adaptor. Make sure the Voltmeter leads are connected so a positive polarity is displayed on the Voltmeter.
    3. Start the engine and allow it to reach normal operating temperature.
    4. Monitor the Voltmeter.

      Is the voltage below 0.5 volt?

      Yes 

      • Go To  7

      No 

      • Repair the excessive resistance in the (K448) ETC Motor (-) circuit.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  7. CHECK THE ETC MOTOR FOR PROPER OPERATION 
    1. Turn the ignition off.
    2. Connect the Throttle Body harness connector.
    3. Measure the resistance of the ETC Motor by probing the GPEC Adaptor across the (K447) ETC Motor (+) circuit and the (K448) ETC Motor (-) circuit.

      Is the resistance between 2.5 and 25 Ohms at closed throttle?

      Yes 

      • Go To  8

      No 

      • Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors. Replace the Throttle Body Assembly if no problems were found in the connectors. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function. Refer to THROTTLE BODY, REMOVAL .
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  8. 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 

      • The wiring or poor connection problem has been repaired.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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