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Diagnostic Test

WARNING: This page is about a different car, the 2016 Jeep Wrangler and 2015 Jeep Wrangler. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR AN ACTIVE DTC 
    1. Diagnose all other DTCs before continuing.
      NOTE:

      Check for contaminants that may have damaged an O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.

    2. Start the engine.
    3. Allow the engine to reach normal operating temperature.
    4. With the scan tool, read DTCs and record on the repair order.
      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. CHECK THE FUEL DELIVERY SYSTEM 
    1. Perform the CHECKING THE FUEL DELIVERY SYSTEM test procedure. Refer to CHECKING THE FUEL DELIVERY SYSTEM (HARD START) .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECK THE EXHAUST SYSTEM FOR LEAKS 
    1. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS test procedure. Refer to CHECKING THE EXHAUST SYSTEM FOR LEAKS .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  4
  4. CHECK THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION 
    NOTE:

    For best results, allow the vehicle to sit long enough for the engine to cool down near ambient temperature.

    1. Turn the ignition on.
    2. With the scan tool, read the Engine Coolant Temperature degree value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.
      NOTE:

      If engine coolant temperature is above 82°C (180°F), allow the engine to cool until 65°C (150°F) is reached.

    3. Start the engine.
    4. During engine warm-up monitor the Engine Coolant Temperature degree value. The temperature value change should be a smooth transition from start up to normal operating temp 82°C (180°F). Also monitor the actual coolant temperature with a digital thermometer at or near the ECT Sensor and Thermostat positions.
      NOTE:

      As the engine warms up to operating temperature, the actual coolant temperature (thermometer reading) and the scan tool Engine Coolant Temperature degree values should stay relatively close to each other.

      Was the digital thermometer readings relatively close to the scan tool reading for the ECT Sensor?

      Yes 

      • Go To  5

      No 

  5. CHECK THE OXYGEN SENSOR OPERATION 
    1. Perform the CHECKING THE OXYGEN SENSOR OPERATION test procedure. Refer to CHECKING THE OXYGEN SENSOR OPERATION .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  6
  6. O2 SENSOR 1/1 HEATER OPERATION 
    1. Turn the ignition off.
      NOTE:

      Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize at 5.0 volts.

    2. Turn the ignition on.
    3. With the scan tool, actuate the O2 Sensor 1/1 Heater Test.
    4. With the scan tool, monitor O2 Sensor 1/1 voltage for at least two minutes.

      Does the voltage stay above 4.5 volts?

      Yes 

      • Verify that there is good pin to terminal contact in the O2 Sensor 1/1 and Powertrain Control Module connectors. Replace the O2 Sensor 1/1 if no problems were found with the connectors. Refer to SENSOR, OXYGEN, REMOVAL .
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  7
  7. CHECK THE MAP SENSOR OPERATION 
    1. Perform the CHECKING THE MAP SENSOR OPERATION test procedure. Refer to CHECKING THE MAP SENSOR OPERATION .

      Were any problems found?

      Yes 

      • Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  8
  8. ENGINE MECHANICAL 
    1. Turn the ignition off.
    2. Check for any of the following conditions/mechanical problems:
      • AIR INDUCTION SYSTEM - must be free from leaks.
      • ENGINE VACUUM - must be at least 13 inches in neutral
      • ENGINE VALVE TIMING - must be within specifications
      • ENGINE COMPRESSION - must be within specifications
      • ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
      • ENGINE PCV SYSTEM - must flow freely
      • TORQUE CONVERTER STALL SPEED - must be within specifications
      • POWER BRAKE BOOSTER - no internal vacuum leaks
      • FUEL - must be free of contamination
      • FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector

      Are there any engine mechanical problems?

      Yes 

      No 

      • Go To  9
  9. CHECK RELATED PCM AND COMPONENT CONNECTIONS 
    1. Perform any Service Bulletins that apply.
    2. Disconnect all PCM harness connectors.
    3. Disconnect all related in-line harness connections (if equipped).
    4. Disconnect the related component harness connectors.
    5. 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.

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

      Did the DTC return?

      Yes 

      No 

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