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Home >> Jeep >> 2024 >> Wagoneer Carbide, RWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Rear Heating And Air Conditioning - DTCS B1052-12 To B108C-15 >> DTC Troubleshooting >> B108B-11 Left Rear Panel Duct Temperature Sensor - Circuit Short To Ground >> 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 CONDITION OF THE TEMPERATURE SENSOR CONNECTOR AND TERMINALS 
    1. Turn the ignition off.
    2. Check the temperature sensor, harness connector and terminals for improper installation, damage, and corrosion.

      Were any problems found?

      Yes 

      • Repair the connector and terminals as necessary.
      • Perform the HVAC VERIFICATION TEST. Refer to: HVAC VERIFICATION TEST .

      No 

      • Go To Next Step.
  3. CHECK THE TEMPERATURE SENSOR SIGNAL CIRCUIT VOLTAGE 
    1. With the ignition off, disconnect the associated temperature sensor harness connector.
    2. Turn the ignition on.
    3. Measure the voltage of the Sensor Signal circuit.

      Is the voltage above 4.7 volts?

      Yes 

      • Go To  6

      No 

      • Go To Next Step.
  4. ISOLATE AND CHECK THE TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    1. The ignition must be off when checking a circuit for continuity to ground.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (HVAC) 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 the negative lead of the Digital Volt-Ohm Meter (DVOM) to a known good ground.
    4. With the positive lead of the DVOM, probe the circuit being tested at the component harness connector and check for continuity between the circuit and ground.
      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 ground and the circuit being tested?

      Yes 

      • Repair the circuit for a short to ground. Use the wiring diagram as a guide to trace the circuit and identify any in-line connectors that may help isolate the location of the short.
      • Perform the HVAC VERIFICATION TEST. Refer to: HVAC VERIFICATION TEST .

      No 

      • Go To Next Step.
  5. ISOLATE AND CHECK THE TEMPERATURE SENSOR 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 HVAC 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 HVAC harness connector.
    4. With the other lead of the DVOM probe all other circuits at the HVAC 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  7
  6. REPLACE THE TEMPERATURE SENSOR 
    1. Turn the ignition off.
    2. Replace the associated temperature sensor in accordance with the service information.
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs.
    5. Turn the ignition off for 10 seconds.
    6. Turn the ignition on.
    7. Turn ON the Heated Seat.
    8. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To Next Step.

      No 

      • The new Temperature Sensor repaired the fault.
      • Perform the HVAC VERIFICATION TEST. Refer to: HVAC VERIFICATION TEST .
  7. 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. Turn the ignition on.
    9. With the scan tool, erase DTCs.
    10. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    11. With the scan tool, read HVAC Module DTCs.

      Did the DTC return?

      Yes 

      No 

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