Diagnostic Test

WARNING: This page is about a different car, the 2025 Jeep Grand 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, read Powertrain Control Module (PCM) DTCs and Freeze Frame Data and record on the repair order.
3. Using the recorded Freeze Frame Data and the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
4. With the scan tool, read DTCs and record on the repair order.
  Is the DTC active or pending?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to: 2.0L - INTERMITTENT CONDITION .
CHECK FOR HIGH RESISTANCE IN THE (N7) FUEL TANK PRESSURE SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the FTP Sensor harness connector.
3. Disconnect the PCM C1 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.
4. Connect the GPEC Diagnostic Adapter [special tool # 10436] to the appropriate PCM harness connector.
  NOTE:
  The GPEC Diagnostic Adaptor can add up to 1.5 Ohms of resistance to the circuit.
5. Measure the resistance of the (N7) Fuel Tank Pressure Signal circuit between the FTP Sensor harness connector and the GPEC Adaptor.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 3
  No
  - Repair the (N7) FTP Signal circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to: 2.0L - POWERTRAIN VERIFICATION TEST .
CHECK FOR HIGH RESISTANCE IN THE (N8) 5-VOLT SUPPLY CIRCUIT
1. Measure the resistance of the (N8) 5-Volt Supply circuit between the FTP Sensor harness connector and the GPEC Adaptor.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 4
  No
  - Repair the (N8) 5-Volt Supply circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to: 2.0L - POWERTRAIN VERIFICATION TEST .
CHECK FOR HIGH RESISTANCE IN THE (N10) SENSOR GROUND CIRCUIT
1. Measure the resistance of the (N10) Sensor Ground circuit between the FTP Sensor harness connector and the GPEC Adaptor.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 5
  No
  - Repair the (N10) Sensor ground circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to: 2.0L - POWERTRAIN VERIFICATION TEST .
CHECK ABILITY OF THE PCM TO READ THE FTP SENSOR SIGNAL
1. Reconnect the PCM C1 harness connector.
2. Turn the ignition on.
3. With the scan tool, monitor the FTP Sensor voltage.
4. Connect a jumper between the (N7) Fuel Tank Pressure Signal circuit and the (N10) Sensor Ground circuit.
  NOTE:
  The FTP Sensor voltage should change from approximately 5.0 volts with the connector unplugged to 0.0 volts with the jumper in place.
  
  Is the voltage reading within the listed specification when the jumper is installed?
  
  Yes
  - Replace the Fuel Tank Pressure Sensor in accordance with the Service Information.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to: 2.0L - POWERTRAIN VERIFICATION TEST .
  No
  - Go To 6
    NOTE:
    Remove the jumper before continuing.
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
  - Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to: 2.0L - POWERTRAIN VERIFICATION TEST .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to: 2.0L - POWERTRAIN VERIFICATION TEST .