Diagnostic Test

WARNING: This page is about a different car, the 2024 Jeep Grand Wagoneer L and 2024 Jeep Grand Wagoneer. However, it is still accessible from the selected car via links, so may be relevant.

READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN
1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
2. For future reference, with the scan tool, run and save a vehicle Scan Report and all related recorded data.
3. With the scan tool, erase all DTCs.
4. Turn the ignition off for a minimum of 10.0 seconds.
5. Turn the ignition on.
6. Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
7. With the scan tool, read DTCs.
  Did the DTC return?
  
  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 5-Volt Supply DTCs active or pending?
  
  Yes
  - Perform the applicable diagnostic procedure(s). Refer to DIAGNOSTIC CODE INDEX .
  No
  - Go To 3
ISOLATE AND CHECK THE FTP SENSOR (N7) PRESSURE SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. The ignition must be off when checking a circuit for continuity to ground.
2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested. Note: Use the wiring diagram as a guide to follow the path of the circuit.
3. Connect the negative lead of the DVOM to a known good ground.
4. With the positive lead of the DVOM, probe the circuit being tested at the component harness connector and check for continuity between the circuit and ground.
  NOTE:
  There should be no continuity between ground and the circuit being tested.
  
  Is there continuity between ground and the circuit being tested?
  
  Yes
  - Repair the circuit for a short to ground. Use the wiring diagram as a guide to trace the circuit and look for any in-line connectors to help isolate the location of the short.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 4
ISOLATE AND CHECK THE FTP SENSOR (N7) PRESSURE SIGNAL CIRCUIT FOR A SHORT TO THE (N10) SENSOR RETURN CIRCUIT
1. The ignition must be off when checking for a short between circuits.
2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested. Note: Use the wiring diagram as a guide to follow the path of the circuit.
3. Connect the test leads of the DVOM and check for continuity between the circuits being tested at the component harness connector.
  NOTE:
  There should be no continuity between the circuits being tested.
  
  Is there continuity between the circuits?
  
  Yes
  - Repair the short between the circuits.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 5
CONNECT A FUSED JUMPER BETWEEN THE FTP SENSOR (N7) PRESSURE SIGNAL CIRCUIT AND THE (N8) SUPPLY CIRCUIT AT THE FTP SENSOR HARNESS CONNECTOR - VERIFY ABILITY OF THE PCM TO DETECT THE SENSOR SIGNAL CIRCUIT HIGH DTC
1. The Electronic Control Module (ECU) harness connectors must be connected to the ECU during this test step.
2. Disconnect the sensor harness connector.
3. With the ignition in the off position, connect a fused jumper between the sensor signal circuit and the Supply circuit at the sensor harness connector.
4. Turn the ignition on.
5. With the scan tool, read DTCs.
  Does the scan tool display the SENSOR SIGNAL CIRCUIT HIGH DTC with the jumper in place?
  
  Yes
  - Replace the faulty sensor in accordance with the Service Information. Refer to SENSOR, FUEL TANK PRESSURE, REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 6
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 POWERTRAIN VERIFICATION TEST .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .