Diagnostic Test

WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

CHECK FOR AN ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, select View DTCs. Copy DTC and Freeze Frame information.
3. With the scan tool, erase DTCs.
4. Operate the vehicle under conditions similar to which the DTC was set.
5. With the scan tool, view the Misfire Monitor to see which cylinders are effected.
  NOTE:
  It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set or to show misfires on a particular cylinder.
  
  Are there excessive misfires shown or is the DTC pending at this time?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK FOR OTHER DTCS
1. Refer to the recorded DTCs.
  Are there any component or circuit DTCs active or pending?
  
  Yes
  - Perform the applicable diagnostic procedure(s). Refer to 3.2L - DIAGNOSTIC CODE INDEX .
  No
  - Go To 3
CHECK FOR AN ACTIVE CONDITION
NOTE:
Anything that affects the speed of the crankshaft can cause a misfire DTC.

NOTE:
When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinder's Injector Control circuit.

NOTE:
Misfires detected during a deceleration are indicators of mechanical concerns.
1. Visually inspect the engine for any of the following conditions:
  - Worn serpentine belt. Refer to BELT, SERPENTINE, DIAGNOSIS AND TESTING .
  - Binding Engine-Driven accessories: A/C Compressor, P/S Pump, Water pump.
  - Misalignment of the Water pump, P/S Pump and A/C Compressor pulleys.
  - Corroded PCM power and ground circuits.
  - Improper CKP, CMP, MAP and TPS mounting.
  - Poor connector/terminal to component connection for CKP Sensor, CMP Sensor, MAP Sensor, TPS, Fuel Injector, Ignition Coil, etc.
  - Vacuum leaks.
  - Restricted Exhaust system. Perform the CHECKING EXHAUST RESTRICTION diagnostic procedure. Refer to DIAGNOSIS AND TESTING .
  - Restricted Air Induction system.
  - Internal engine component failures.
  - Overfilled engine oil or transmission.
  - Extremely out of balance tires or warped brake rotors.
  Were any of the above conditions present?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  No
  - Go To 4
CHECK THE O2 SENSOR FOR PROPER OPERATION
1. Start the engine and allow it to idle long enough for the O2 Sensor to warm up and go into closed loop operation. This may take a couple of minutes.
2. With the scan tool, observe the voltage reading of the Downstream O2 Sensor for the bank on which the misfire was present.
  NOTE:
  If the misfire is caused by a lack of fuel condition, the O2 Sensor voltage will tend to stay at the low end of the range (approximately 2.5 volts). If the misfire is caused by a lack of or poor quality spark condition, the O2 Sensor voltage will tend to stay at the high end of the voltage range (approximately 3.5 volts).
  
  Does the Downstream O2 Sensor voltage reading tend to be staying at the low end (2.5 volts) or high end (3.5 volts) of the voltage range.
  
  High end of the range (3.5 volts)
  - Go To 5.
  Low end of the range (2.5 volts)
  - Go To 8.
CHECK THE IGNITION SYSTEM FOR PROPER OPERATION
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.

NOTE:
When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinder's Injector Control circuit. It may be necessary to erase the DTC or reset the misfire monitor before proceeding with this step in order for the PCM to fire the Ignition Coil.
1. Turn the ignition off.
2. Remove the Ignition Coil of the cylinder that is misfiring. For Multiple Cylinder Misfire, check each Ignition Coil individually. Refer to COIL, IGNITION, REMOVAL, 3.2L .
3. Reconnect the Ignition Coil harness connector.
4. Disconnect the Fuel Injector harness connector of the cylinder being tested.
5. Install a spark tester on the Ignition Coil.
6. While cranking the engine observe the spark coming from the spark tester.
  NOTE:
  A crisp blue spark that is able to jump the gap of the spark tester should be generated at the coil on plug.
  
  Is good spark present?
  
  Yes
  - Go To 6
  No
  - Go To 12
    NOTE:
    Reconnect the Fuel Injector harness connector before continuing.
CHECK THE SPARK PLUG FOR DAMAGE
1. Turn the ignition off.
2. Remove the Spark Plug(s) in accordance with the service information. Refer to SPARK PLUG, REMOVAL, 3.2L .
3. Inspect the Spark Plug(s) for the following conditions:
  - Cracks
  - Carbon Tracking
  - Foreign Material
  - Gap size out of specifications
  - Loose or broken electrode
  NOTE:
  Lightly tap the bottom of the spark plug on a solid surface. The electrode in the spark plug should not move.
  
  Were any of the above conditions present?
  
  Yes
  - Replace the Spark Plug in accordance with the service information. Refer to SPARK PLUG, REMOVAL, 3.2L .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  No
  - Go To 7
CHECK THE SPARK PLUG FOR PROPER OPERATION
1. Turn the ignition off.
2. Exchange the Spark Plug with a known good cylinder that was not indicating a misfire.
3. Start the engine and monitor the misfire monitor screen.
  Did the misfire switch to the previously good cylinder?
  
  Yes
  - Replace the Spark Plug in accordance with the service information. Refer to SPARK PLUG, REMOVAL, 3.2L .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  No
  - Go To 11
CHECK THE FUEL SYSTEM FOR PROPER OPERATION
1. Perform the CHECKING THE FUEL DELIVERY SYSTEM test procedure. Refer to CHECKING THE FUEL DELIVERY SYSTEM (HARD START) .
  NOTE:
  Fuel pressure specification is 400 kPa +/- 14 kPa (58 psi +/- 2 psi).
  
  Were any problems found with the fuel system?
  
  Yes
  - Perform the appropriate repairs.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  No
  - Go To 9
CHECK THE FUEL INJECTOR FOR PROPER OPERATION
1. Turn the ignition off.
2. Disconnect the Fuel Injector harness connector of the misfiring cylinder. For Multiple Cylinder Misfire, check each Fuel Injector individually.
3. Ignition on, engine not running.
  NOTE:
  When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinder's Injector Control circuit. It may be necessary to erase the DTC or reset the misfire monitor before proceeding with this step in order for the PCM to fire the Fuel Injector.
4. Install an Injector Noid light.
5. With the scan tool, actuate the Fuel Injector.
  Does the Noid light blink/flicker during the actuation?
  
  Yes
  - Verify that there is good pin to terminal contact in the related Injector and the Powertrain Control Module connectors. Replace the Fuel Injector. Refer to INJECTOR(S), FUEL, REMOVAL, 3.2L .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  No
  - Go To 10
CHECK THE INJECTOR CONTROL CIRCUIT FOR A SHORT TO GROUND, SHORT TO VOLTAGE, OR AN OPEN
1. Turn the ignition off.
2. Remove the Injector Noid light.
3. Disconnect the PCM C2 harness connector.
4. Check the Injector Control circuit for an open, short to ground and short to voltage.
  Was a problem found with the Injector Control circuit?
  
  Yes
  - Repair the excessive resistance or short in the Injector Control circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  No
  - Go To 12
CHECK THE ENGINE FOR MECHANICAL PROBLEMS
1. Check for any of the following conditions/mechanical problems:
  - ENGINE VACUUM - must be at least 13 inches in neutral
  - ENGINE VALVE TIMING - must be within specifications
  - ENGINE COMPRESSION - must be within specifications
  - CYLINDER LEAKAGE TEST - 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
  - VALVE SPRINGS - cannot be weak or broken
  - CAM LOBES - must not be worn excessively
  - CAM SHAFTS - must not be worn or have excessive end play
  Are there any engine mechanical problems?
  
  Yes
  - Repair as necessary.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  No
  - Go To 16
CHECK THE (F343) ASD RELAY OUTPUT CIRCUIT FOR AN OPEN OR SHORT TO GROUND
NOTE:
The following test steps will apply to the suspect cylinder from step 4.
1. Turn the ignition off.
2. Disconnect the Coil on Plug harness connector.
3. Ignition on, engine not running.
4. With a scan tool, actuate the ASD Relay.
5. Using a 12-Volt test light connected to ground, probe the (F343) ASD Relay Output circuit at the Coil on Plug harness connector.
  Does the test light illuminate brightly?
  
  Yes
  - Go To 13
  No
  - Repair the open or short to ground in the (F343) ASD Relay Output circuit between the PDC and Coil on Plug harness connector.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
CHECK THE IGNITION COIL FOR PROPER OPERATION
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.
1. Using a 12-Volt test light connected to a 12 Volt source, probe the Coil Control circuit at the Coil on Plug harness connector.
2. Crank the engine for 5.0 seconds while observing the test light.
  What is the condition of the test light while cranking the engine?
  
  Brightly blinking.
  - Replace the Ignition Coil in accordance with the service information.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  ON constantly.
  - Go To 14
  OFF constantly.
  - Go To 15
CHECK THE COIL CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance between ground and the Coil Control circuit at the Coil on Plug harness connector.
  Is the resistance above 10k Ohms?
  
  Yes
  - Go To 15
  No
  - Repair the Coil Control circuit for a short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
CHECK THE COIL CONTROL CIRCUIT FOR AN OPEN/HIGH 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).
4. Measure the resistance of the Coil Control circuit between the Coil on Plug harness connector and the GPEC Adaptor.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Go To 16
  No
  - Repair the Coil Control circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
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
  - Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL, 3.2L .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST, 3.2L .