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Home >> Jeep >> 2024 >> Wagoneer Base, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 51 (3.0L - DTCS U0129-00 To U0417-00) >> DTC Troubleshooting >> U02A9-00-Lost Communication With Charge Air Cooler Coolant Pump "A" >> Diagnostic Test

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.
  1. CHECK FOR ANY SERVICE BULLETINS OR PCM SOFTWARE UPDATES 
    1. Check for any applicable Service Bulletins or Flash updates related to the DTC.

      Are there any applicable Service Bulletins or Flash updates?

      Yes 

      No 

      • Go To Next Step
  2. 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 Next Step

      No 

  3. INSPECT THE LOW TEMP COOLANT PUMP FOR SIGNS OF PHYSICAL DAMAGE 
    1. Inspect the Low Temp Cooler Coolant Pump and connector for damage due to road debris.

      Is the Charge Air Cooler Coolant Pump or connector damaged or disconnected?

      Yes 

      No 

      • Go To Next Step
  4. 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 Auxiliary Coolant Pump. 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 AGS.
    3. Disconnect the lower AGS (If equipped).
    4. Disconnect the Three way coolant valve (If equipped).
    5. Disconnect the Active Air Dam (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
  5. CHECK THE (A501) FUSED B+ CIRCUIT VOLTAGE 
    1. Turn the ignition off.
    2. Disconnect the Charge Air Cooler Coolant Pump harness connector.
    3. Turn the ignition on.
    4. Measure the voltage on the (A501) Fused B+ circuit at the Charge Air Cooler Coolant Pump harness connector.

      Is the voltage equal to battery voltage?

      Yes 

      • Go To Next Step

      No 

      • Repair the (A501) Fused B+ circuit for an open or short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. CHECK THE LOW TEMP COOLER PUMP (Z921) GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Measure the resistance between ground and the (Z921) Ground circuit at the Charge Air Cooler Coolant Pump harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To Next Step

      No 

      • Repair the (Z921) Ground circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  7. CHECK THE (D511) LIN BUS CIRCUITS FOR A SHORT TO GROUND 
    1. Disconnect the PCM C1 harness connector.
    2. Check for continuity between ground and the (D511) LIN BUS circuit at the Charge Air Cooler Coolant Pump harness connector.

      Is there continuity between ground and the (D511) LIN BUS circuit?

      Yes 

      • Repair the (D511) LIN BUS circuit for a short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To Next Step
  8. CHECK THE (D511) LIN BUS CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Measure the resistance of the (D511) LIN BUS circuit between the Charge Air Cooler Coolant Pump harness connector and the PCM C1 harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To Next Step

      No 

      • Repair the (D511) LIN BUS circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  9. LOW TEMP COOLER COOLANT PUMP 
    1. Replace the Low Temp Cooler Coolant Pump in accordance with the Service Information.
    2. Reconnect the PCM C1 harness connector.
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs.
    5. Cycle the ignition off, then back on
    6. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To Next Step

      No 

      • Replacing the Low Temp Cooler Coolant Pump repaired the fault.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  10. 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 

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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