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Home >> Jeep >> 2022 >> Gladiator Mojave, Part Time T/Case Control, Standard Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 34 (3.0L Diesel - DTCS U0140-00 To U04B1-00) >> DTC Troubleshooting >> U02A5-00-Lost Communication With REDUCTANT Heater Control Module >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR AN ACTIVE DIAGNOSTIC TEST CODE (DTC) 
    1. Ignition on, engine not running.
    2. With the scan tool, erase DTCs in the PCM.
    3. Start the engine.
    4. Allow the engine to reach normal operating temperature.
    5. Test drive the vehicle under normal operating conditions.
      NOTE:

      During cold ambient temperatures, it may be necessary to test drive the vehicle for an extended period to properly cycle the fail conditions for this DTC.

    6. With the scan tool, select View DTCs.

      Is the status Active for this DTC?

      Yes 

      • Go To  2

      No 

      • Perform to the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT DTC .
  2. CHECK THE (D468) LOW DATA LINK (-) CIRCUIT FOR A SHORT TO OTHER CIRCUITS IN THE PCM C1 HARNESS CONNECTOR 
    1. Turn the ignition off.
    2. Disconnect the DEF HCU harness connector.
    3. Disconnect the PCM C1 harness connector.
    4. Measure the resistance between the (D468) Low Data Link (-) circuit and all other circuits on the PCM C1 harness connector at the PCM C1 harness connector.

      Is the resistance above 10k Ohms on all other circuits?

      Yes 

      • Go To  3

      No 

      • Repair the (D468) Low Data Link (-) circuit for a short to the circuit that measured less than 10k Ohms.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to 3.0L, POWERTRAIN VERIFICATION TEST .
  3. CHECK THE (D468) LOW DATA LINK (-) CIRCUIT FOR A SHORT TO GROUND 
    1. Measure the resistance between ground and the (D468) Low Data Link (-) circuit at the DEF HCU harness connector.

      Is the resistance above 10k Ohms?

      Yes 

      • Go To  4

      No 

  4. CHECK THE (D468) LOW DATA LINK (-) CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Measure the resistance of the (D468) Low Data Link (-) circuit between the DEF HCU harness connector and the PCM C1 harness connector.

      Is the resistance above 5.0 Ohms?

      Yes 

      No 

      • Go To  5
  5. CHECK THE (D469) HIGH DATA LINK (+) CIRCUIT FOR A SHORT TO OTHER CIRCUITS IN THE PCM C1 HARNESS CONNECTOR 
    1. Measure the resistance between the (D469) High Data Link (+) circuit and all other circuits on the PCM C1 harness connector at the PCM C1 harness connector.

      Is the resistance above 10k Ohms on all other circuits?

      Yes 

      • Go To  6

      No 

      • Repair the (D469) High Data Link (+) circuit for a short to the circuit that measured less than 10k Ohms.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to 3.0L, POWERTRAIN VERIFICATION TEST .
  6. CHECK THE (D469) HIGH DATA LINK (+) CIRCUIT FOR A SHORT TO GROUND 
    1. Measure the resistance between ground and the (D469) High Data Link (+) circuit at the DEF HCU harness connector.

      Is the resistance above 10k Ohms?

      Yes 

      • Go To  7

      No 

  7. CHECK THE (D469) HIGH DATA LINK (+) CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Measure the resistance of the (D469) High Data Link (+) circuit between the DEF HCU harness connector and the PCM C1 harness connector.

      Is the resistance above 5.0 Ohms?

      Yes 

      No 

      • Go To  8
  8. CHECK THE (F343) ASD SUPPLY CIRCUIT, (A914) FUSED B+ CIRCUIT AND THE (Z909) HCU GROUND CIRCUIT FOR A SHORT TO GROUND OR AN OPEN/HIGH RESISTANCE 
    1. Reconnect the PCM C1 harness connector.
    2. Turn the ignition on, engine off.
    3. Measure the voltage across the (F343) ASD Supply circuit and the (Z909) HCU Ground circuit at the DEF HCU harness connector. Then, measure the voltage across the (A914) Fused B+ circuit and the (Z909) HCU Ground circuit at the DEF HCU harness connector.

      Was the difference of either voltage reading greater than 1.0 Volts of battery voltage?

      Yes 

      • Repair the (F343) ASD Supply circuit or the (A914) Fused B+ circuit for an open or short to ground, or check the (Z909) Ground circuit for an open.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to 3.0L, POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  9
  9. CHECK FOR DAMAGED WIRES OR DAMAGED TERMINALS 
    1. Turn the ignition off.
    2. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the DEF HCU and the PCM.
    3. Look for any chafed, pierced, pinched, or partially broken wires.
    4. Look for broken, bent, pushed out or corroded terminals.

      Were any problems found?

      Yes 

      No 

      • Go To  10
  10. CHECK THE DEF HCU FOR PROPER OPERATION 
    1. Replace the DEF Heater Control Unit (HCU) in accordance with the service information.
    2. Turn the ignition on.
    3. With the scan tool, erase PCM DTCs.
    4. Start the engine and run it until it reaches operating temperature.
    5. Test drive the vehicle under normal operating conditions.
      NOTE:

      During cold ambient temperatures, it may be necessary to test drive the vehicle for an extended period to properly cycle the fail conditions for this DTC.

    6. With the scan tool, read PCM DTCs.

      Does the scan tool display this DTC?

      Yes 

      • Go To  11

      No 

  11. 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.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to 3.0L, POWERTRAIN VERIFICATION TEST .

      No 

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