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.

CHECK FOR AN ACTIVE DTC
1. Start the engine and allow it to idle.
2. With the scan tool, read PCM DTCs.
  Is this DTC active or pending?
  
  Yes
  - Go To Next Step
  No
  - Perform the INTERMITTENT DTC diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK THE COMPONENTS THAT SHARE THE LIN
1. IMPORTANT - FOLLOW THIS PROCEDURE EXACTLY WHEN CHECKING THE FOLLOWING COMPONENTS: Turn the ignition off before disconnecting each component. After a component has been disconnected, turn the ignition on and test the function of the Alternator. If the fault does not return after disconnecting a component, the component that was disconnected is faulty. If the fault remains after disconnecting a component, then the disconnected component is not the problem. Leave each component disconnected and move on to the next until the faulty component is discovered or all components have been disconnected. Disconnect only one component at a time during this step.
2. Disconnect the upper Active Air Dam (If equipped).
3. Disconnect the upper AGS (If equipped).
4. Disconnect the lower AGS (If equipped).
5. Disconnect the Three way coolant valve (If equipped).
6. Disconnect the Auxiliary Coolant Pump (If equipped).
  Were any of the above components determined to be at fault?
  
  Yes
  - Replace the faulty component in accordance with the Service Information.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To Next Step
CHECK FOR HIGH RESISTANCE IN THE (D511) LIN BUS CIRCUIT
1. Turn the ignition off.
2. Disconnect the Alternator LIN BUS harness connector.
3. Disconnect the PCM C2 harness connector.
4. Measure the resistance of the (D511) LIN Bus circuit between the Alternator harness connector and PCM C2 harness connector.
  Is the resistance below 2.0 Ohms?
  
  Yes
  - Go To Next Step
  No
  - Repair the (D511) LIN Bus circuit for a an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
REPLACE THE ALTERNATOR AND RETEST FOR DTC
1. Replace the Alternator in accordance with the Service Information. Refer to GENERATOR, REMOVAL AND INSTALLATION .
2. Reconnect the Alternator LIN BUS and PCM harness connectors.
3. Turn the ignition on.
4. With the scan tool, erase PCM DTCs.
5. Using the Freeze Frame Data or When Monitored Conditions above, operate the vehicle within the conditions that set the DTC.
6. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Go To Next Step
  No
  - Replacing the Alternator repaired the fault.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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 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 .