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Home >> Alfa Romeo >> 2019 >> Giulia Base, AWD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> (Heating & Air Conditioning - Electrical Diagnostics) >> DTC Troubleshooting >> B1931-15 - Internal Temperature Sensor-Circuit Short To Battery Or Open >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    1. With the scan tool, read HVAC DTCs and record on the repair order.
    2. Record the Environmental Data.
    3. With the scan tool, erase DTCs.
    4. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    5. With the scan tool, read HVAC DTCs.

      Did the DTC return?

      Yes 

      • Go To  2

      No 

  2. CHECK THE HARNESS CONNECTORS FOR PROPER CONNECTION 
    1. Check for loose, damaged or corroded connections on the In-Car Temperature Sensor harness connector and HVAC Module harness connector.

      Are there any loose or damaged connectors?

      Yes 

      • Repair the harness connectors as necessary.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Go to Step  3.
  3. CHECK THE (F741) IGNITION RUN/START OUTPUT CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Turn the Ignition off.
    2. Disconnect the In-Car Temperature Sensor harness connector.
    3. Disconnect the HVAC Module harness connector.
    4. Using a multimeter, check the resistance of the (F741) Ignition Run/Start Output circuit between pin 3 of the In-Car Temperature Sensor harness connector and pin 59 of the HVAC Module harness connector.

      Is the resistance above 3.0 Ohms?

      Yes 

      • Repair the (F741) Ignition Run/Start Output circuit for an open circuit or high resistance.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Go to  4
  4. CHECK THE (F741) IGNITION RUN/START OUTPUT CIRCUIT FOR A SHORT TO BATTERY 
    1. Turn the Ignition on.
    2. Using a multimeter, check for voltage in the (F741) Ignition Run/Start Output circuit between pin 3 of the In-Car Temperature Sensor harness connector and pin 59 of the HVAC Module harness connector.

      Is there a short circuit to voltage in the (F741) Ignition Run/Start Output circuit?

      Yes 

      • Repair the (F741) Ignition Run/Start Output circuit for a short circuit to the battery.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Go To  5
  5. CHECK THE IN-CAR TEMPERATURE SENSOR FOR PROPER OPERATION 
    1. Replace the In-Car Temperature Sensor in accordance with the Service Information. Refer to SENSOR, TEMPERATURE, IN-CAR, REMOVAL AND INSTALLATION .
    2. With the scan tool, erase HVAC DTCs.
    3. With the scan tool, read DTCs.

      Did this DTC reset?

      Yes 

      • Go To  6

      No 

  6. 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 

      • Repair any faulty connections.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
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