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Home >> Jeep >> 2024 >> Wagoneer Carbide, RWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating And Air Conditioning (ATC) - DTCS B10B2-00 To B10E8-12 >> DTC Troubleshooting >> B10C8-15-Blower Motor Control Feedback Circuit-Circuit Short To Battery Or Open >> 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. With the scan tool, run a Vehicle Scan Report or record the Environmental Data.
    3. With the scan tool, erase DTCs.
    4. Turn the ignition off for at least 10.0 seconds.
    5. Turn the ignition on.
    6. Using the recorded Environmental Data and the When Monitored Conditions, 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 

  2. CHECK THE FUSED B+ CIRCUIT AT THE BLOWER MOTOR 
    1. Turn the ignition off.
      NOTE:

      DIAGNOSE AND REPAIR ALL LIN BUS RELATED DTC'S BEFORE PERFORMING THIS TEST PROCEDURE 

    2. Disconnect the Blower Motor harness connector.
    3. Turn the ignition on.
    4. Connect one end of the test light to ground.
    5. With the test light probe the Fused B+ circuit at the blower motor harness connector.

      Does the test light illuminate brightly?

      Yes 

      • Go To Next Step.

      No 

      • Repair the open Fused B+ circuit to the Blower Motor connector.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  3. CHECK THE GROUND CIRCUIT AT THE BLOWER MOTOR 
    1. Turn the ignition off.
      NOTE:

      DIAGNOSE AND REPAIR ALL LIN BUS RELATED DTC'S BEFORE PERFORMING THIS TEST PROCEDURE 

    2. Disconnect the Blower Motor harness connector.
    3. Turn the ignition on.
    4. Connect one end of the test light to 12 volts.
    5. With the test light probe the Ground circuit at the blower motor harness connector.

      Does the test light illuminate brightly?

      Yes 

      • Go To Next Step.

      No 

      • Repair the open Ground circuit to the Blower Motor connector.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  4. CHECK THE (C229) BLOWER RETURN CIRCUIT FOR AN OPEN OR HIGH RESISTANCE 
    1. Turn the Ignition off.
    2. Disconnect the HVAC Module harness connector.
    3. Measure the resistance of the Blower Return Circuit between the Blower Module and the HVAC Module harness connectors.

      Is the resistance below 3.0 ohms?

      Yes 

      • Go To Next Step.

      No 

  5. CHECK THE (C56) BLOWER PWM SIGNAL CIRCUIT FOR AN OPEN OR HIGH RESISTANCE 
    1. Measure the resistance of the Blower PWM Signal Circuit between the Blower Module and the HVAC Module harness connectors.

      Is the resistance below 3.0 ohms?

      Yes 

      • Go To Next Step.

      No 

  6. ISOLATE AND CHECK THE (C229) BLOWER RETURN CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE HVAC MODULE 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 ECU and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit. Check the disconnected connectors and related harnesses for damage, corrosion, and loose fitting terminals.
    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 back-probing a circuit at a harness connector, always use an appropriate back probing tool to prevent damage to the connector terminals.

      Is there continuity between the circuit being tested and any other circuit?

      Yes 

      • Repair the circuit for a short to another circuit. Use the wiring diagram as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

      No 

      • Go To Next Step.
  7. ISOLATE AND CHECK THE (C56) BLOWER PWM SIGNAL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE HVAC MODULE 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 ECU and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram as a guide to follow the path of the circuit. Check the disconnected connectors and related harnesses for damage, corrosion, and loose fitting terminals.
    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 back-probing a circuit at a harness connector, always use an appropriate back probing tool to prevent damage to the connector terminals.

      Is there continuity between the circuit being tested and any other circuit?

      Yes 

      • Repair the circuit for a short to another circuit. Use the wiring diagram as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

      No 

      • Go To Next Step.
  8. REPLACE THE BLOWER MOTOR POWER MODULE AND CHECK FOR THE DTC TO RETURN 
    1. Replace the Blower Motor in accordance with the Service Information. Refer to MODULE, POWER, REAR BLOWER MOTOR, REMOVAL AND INSTALLATION .
    2. Connect the Blower Motor, ECU, and any other disconnected harness connectors.
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs.
    5. Using the recorded Environmental Data and the When Monitored conditions, operate the vehicle in 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 Blower Motor corrected the condition.
      • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  9. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all HVAC Module 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.
      • Perform a terminal drag test on each connector terminal to verify proper terminal tension.

      Repair any conditions that are found.

    5. Reconnect all HVAC Module harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect 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. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    10. With the scan tool, read HVAC Module DTCs.

      Did the DTC return?

      Yes 

      No 

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