LEMON Manuals: Even more car manuals for everyone: 1960-2025
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 >> B1940-17 - Cabin Fan-Circuit Voltage Above Threshold >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    1. With the scan tool, read 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 Module DTCs.

      Did the DTC return?

      Yes 

      • Go To  2

      No 

      • Perform the TESTING FOR AN INTERMITTENT CONDITION procedure. Refer to STANDARD PROCEDURE .
  2. CHECK VOLTAGE AT THE BLOWER MOTOR POWER MODULE (F745) GENERIC IGNITION RUN START CIRCUIT 
    1. Disconnect the Blower Motor Power Module C1 harness connector.
    2. Turn the ignition on.
    3. Measure voltage on the (F745) Generic Ignition Run Start circuit at the Blower Motor Power Module harness connector.

      Is the voltage about equal to battery voltage?

      Yes 

      • Go To  3

      No 

      • Repair the open or short to ground on the (F745) Generic Ignition Run Start circuit.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  3. CHECK THE (Z210) GROUND CIRCUIT FOR AN OPEN OR HIGH RESISTANCE 
    1. Measure the resistance of the (Z210) Ground circuit between the Blower Motor Power Module C1 harness connector and ground.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  4

      No 

      • Repair the (Z210) Ground circuit for an open or high resistance.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  4. CHECK (C7) BLOWER MOTOR SUPPLY CIRCUIT FOR VOLTAGE 
    1. Connect the Blower Motor Power Module C1 harness connector.
    2. Disconnect the Blower Motor harness connector.
    3. Turn the ignition on and command the blower speed to HIGH.
    4. Measure voltage on the (C7) Blower Motor Supply circuit at the Blower Motor harness connector.

      Is the voltage near battery voltage?

      Yes 

      • Go To  5

      No 

      • Go To  6
  5. CHECK THE (C56) BLOWER MOTOR CONTROL CIRCUIT PULSE WIDTH MODULATED (PWM) SIGNAL 
    1. Turn the ignition on and command the blower speed to HIGH.
    2. Measure the PWM Signal on the (C56) Blower Motor Control circuit at the Blower Motor harness connector.

      Is the PWM Signal above 80%?

      Yes 

      No 

      • Go To  6
  6. CHECK THE HARNESS BETWEEN THE BLOWER MOTOR AND THE POWER MODULE 
    1. Inspect the harness between the Blower Motor and Power Module for damage that could cause an open or short.

      Were any problems found?

      Yes 

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

      No 

      • Go To  7
  7. CHECK THE (C56) BLOWER MOTOR CONTROL CIRCUIT FOR AN OPEN OR HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the Blower Motor Power Module C2 harness connector.
    3. Disconnect the HVAC Module harness connector.
    4. Measure the resistance of the (C56) Blower Motor Control circuit between the HVAC Module harness connector and the Blower Motor Power Module harness connector terminal 3.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  8

      No 

      • Repair the (C56) Blower Motor Control circuit for an open or high resistance.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  8. CHECK THE (C56) BLOWER MOTOR CONTROL CIRCUIT FOR A SHORT TO GROUND 
    1. Check for continuity between ground and the (C56) Blower Motor Control circuit at the HVAC Module harness connector terminal 3.

      Is there continuity between ground and the (C56) Blower Motor Control circuit?

      Yes 

      • Repair the (C56) Blower Motor Control circuit for a short to ground.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Go To  9
  9. CHECK THE (C56) BLOWER MOTOR CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT 
    1. Check for continuity between the (C56) Blower Motor Control circuit and all other circuits at the HVAC Module harness connector.

      Is there continuity between the (C56) Blower Motor Control circuit and any other circuit?

      Yes 

      • Repair the (C56) Blower Motor Control circuit for a short to another circuit.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Go To  10
  10. CHECK THE (C806) BLOWER MOTOR RETURN CIRCUIT FOR AN OPEN OR HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the Blower Motor return Module C2 harness connector.
    3. Disconnect the HVAC Module harness connector.
    4. Measure the resistance of the (C806) Blower Motor Return circuit between the HVAC Module harness connector and the Blower Motor Power Module harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  11

      No 

      • Repair the (C806) Blower Motor Return circuit for an open or high resistance.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  11. CHECK THE (C806) BLOWER MOTOR RETURN CIRCUIT FOR A SHORT TO GROUND 
    1. Check for continuity between ground and the (C806) Blower Motor Return circuit at the HVAC Module harness connector.

      Is there continuity between ground and the (C806) Blower Motor Control circuit?

      Yes 

      • Repair the (C806) Blower Motor Return circuit for a short to ground.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Go To  12
  12. CHECK THE (C806) BLOWER MOTOR RETURN CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT 
    1. Check for continuity between the (C806) Blower Motor Return circuit and all other circuits at the HVAC Module harness connector.

      Is there continuity between the (C806) Blower Motor Return circuit and any other circuit?

      Yes 

      • Repair the (C806) Blower Motor Return circuit for a short to another circuit.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .

      No 

      • Go To  13
  13. REPLACE THE BLOWER MOTOR POWER MODULE AND CHECK FOR THE DTC TO RETURN 
    1. Replace the Blower Motor power Module in accordance with the Service Information. Refer to MODULE, POWER, BLOWER MOTOR, REMOVAL AND INSTALLATION .
    2. Reconnect all previously disconnected connectors.
    3. With the scan tool, erase DTCs.
    4. Operate the vehicle in the conditions that originally set the DTC or use the When Monitored conditions.
    5. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To  14

      No 

      • The new Blower Motor Power Module repaired the problem.
      • Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  14. 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 STANDARD PROCEDURE .
scientia non olet · About LEMON Manuals