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Home >> Jeep >> 2021 >> Grand Cherokee L Laredo, RWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating & Air Conditioning (ATC) - DTCS B1E9C-11 To U1480-00 >> Diagnosis And Testing >> B1E9C-12-Rear Right Heater Control 1-Circuit Short To Battery >> Diagnostic Test

Diagnostic Test

  1. 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 

  2. PERFORM THE APPROPRIATE HVAC ACTUATOR CALIBRATION / AUTO ADDRESSING ROUTINE TEST AND CHECK FOR THE DTC TO RETURN 
    NOTE:

    NO HVAC mode or temp functions will perform as desired unless auto-addressing was successful. 

    NOTE:

    NO Heated/Vented Seats functions will operate unless auto-addressing was successful. 

    NOTE:

    Auto-addressing needs to be done every time a CSM/CSWSM/CRSM or an Actuator is replaced. 

    NOTE:

    Diagnose and repair all LIN Bus related DTC's before performing this test procedure. 

    With the scan tool, perform the appropriate HVAC Actuator Calibration/Auto Addressing Routine and recheck DTCs.

    Did any of the above test routines fail?

    Yes 

    • Replace the faulty component that failed the HVAC Actuator Calibration/Auto Addressing Routine and or LIN issue in Accordance with the Service Information.
    • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

    No 

  3. CHECK THE (P873) REAR RIGHT SEAT BACK HEATER FEED CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Turn the ignition off.
    2. Disconnect the Comfort Seat Module (CSM) harness connector.
    3. Start the engine.
    4. Measure the voltage of the (P873) Rear Right Seat Back Heater Feed circuit in the CSM harness connector.

    Is the voltage above 16.0 volts?

    Yes 

    • Repair the (P873) Rear Right Seat Back Heater Feed circuit for a short to voltage.
    • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

    No 

    • Go To  4
  4. ISOLATE AND CHECK THE (P873) REAR RIGHT SEAT BACK HEATER FEED CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE CSM HARNESS CONNECTOR 
    1. The ignition must be off when performing a resistance check to find 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. At this time leave all in-line connectors connected. Note: Use the appropriate wiring information as a guide to follow the path of the circuit.
    3. Connect one lead of the DVOM to the circuit being tested at the ECU harness connector.
    4. With the other lead of the DVOM probe all other circuits at the ECU harness connector.
    NOTE:

    When probing a circuit at an Electronic Control Unit (ECU) harness connector, always use an appropriate back probing tool to prevent any possible damage to the ECU terminals.

    NOTE:

    With the circuit isolated there should be no continuity between the circuit being tested and any other circuit.

    Is there continuity between the (P873) Rear Right Seat Back Heater Feed circuit and any other circuit?

    Yes 

    • Repair the short between the circuits that have continuity. Use the appropriate wiring information as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
    • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

    No 

    • Go To  5
  5. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all CSM 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 CSM 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 CSM DTCs.

      Is the same DTC active?

      Yes 

      • Replace the Comfort Seat Module (CSM) in accordance with the Service Information.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Repairing the wiring harness or connections corrected the problem.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
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