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Blower Motor Malfunction

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Blower Motor Control Module B+

B0193 06

B0193 06

--

--

Blower Motor B+

1

1

--

--

Blower Motor Control Module Control

B0193 06

B0193 06

B0193 01

--

Blower Motor Control

2

1

1

--

Blower Motor Control Module Ground

--

B0193 06

--

--

1. Blower Motor Inoperative

2. Blower Motor Always ON

Circuit/System Description

The blower motor control module is an interface between the HVAC control module and the blower motor. The blower motor speed control input from the HVAC control module, battery positive and ground circuits enable the blower motor control module to operate. The HVAC control module provides a pulse width modulation (PWM) signal to the blower motor control module in order to command the blower motor speed. The blower motor control module transfers the PWM signal into a corresponding blower motor voltage, varying between 2-13 V, linear to the frequency of the PWM signal.

Diagnostic Aids

Check the following mechanical fault sources

    • Air distribution box
    • Air distribution hoses/air distribution ducts

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Symptoms - HVAC Systems - Automatic

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition OFF. Verify the M8 Blower Motor is OFF.
    2. [ARW-LISTFAIL]

  2. If the M8 Blower Motor is ON

    Refer to Circuit/System Testing below.

    3. [/ARW-LISTFAIL][ARW-LISTPASS]

  3. If the M8 Blower Motor is OFF

    4. [/ARW-LISTPASS]
  4. Ignition ON. Set A26 HVAC Controls to Defrost Mode, operate the Blower Motor Switch through all stages. Verify the M8 Blower Motor operates and changes speed according to selection.
    5. [ARW-LISTFAIL]

  5. If the M8 Blower Motor does not operate and changes speed as selected

    Refer to Circuit/System Testing below.

    6. [/ARW-LISTFAIL][ARW-LISTPASS]

  6. If the M8 Blower Motor does operate and changes speed as selected

    7. [/ARW-LISTPASS]
  7. Verification complete. Refer to Testing for Intermittent Conditions and Poor Connections .

Circuit/System Testing

  1. Ignition ON. Set the Blower Motor Switch stepwise from LOW to HIGH. With a scan tool, verify the Blower Motor Switch parameter reflects the selected blower speed.
    2. [ARW-LISTFAIL]

  2. If the scan tool reading does not reflect the selected speed

    Replace the A26 HVAC Controls.

    3. [/ARW-LISTFAIL][ARW-LISTPASS]

  3. If the scan tool reading matches the selected speed

    4. [/ARW-LISTPASS]

    Note: It may take up to 2 minutes for all vehicle systems to power down.

  4. Ignition OFF. Disconnect the harness connector X1 at the K8 Blower Motor Control Module.
  5. Ignition ON Test for less than 1 V on the ground circuit connector terminal 5 X1 and ground.
    6. [ARW-LISTFAIL]

  6. If 1 V or greater

    Repair the short to voltage in the circuit.

    7. [/ARW-LISTFAIL][ARW-LISTPASS]

  7. If less than 1 V

    8. [/ARW-LISTPASS]
  8. Test for less than 5 Ω between the ground circuit connector terminal 5 X1 and ground.
    9. [ARW-LISTFAIL]

  9. If 5 Ω or greater

    10. [/ARW-LISTFAIL]
    4.1. Ignition OFF.
    4.2. Test for less than 2 Ω in the ground circuit end to end.
    [ARW-LISTFAIL]

  10. If 2 Ω or greater, repair the open/high resistance in the circuit.

  11. If less than 2 Ω, repair the open/high resistance in the ground connection.

    12. [/ARW-LISTFAIL] [ARW-LISTPASS]

  12. If less than 5 Ω

    13. [/ARW-LISTPASS]
  13. Verify a test lamp illuminates between the B+ circuit connector terminal 6 X1 and ground.
    14. [ARW-LISTFAIL]

  14. If the test lamp does not illuminate and the circuit fuse is good

    15. [/ARW-LISTFAIL]
    5.1. Ignition OFF.
    5.2. Test for less than 2 Ω in the B+ circuit end to end.
    [ARW-LISTFAIL]

  15. If 2 Ω or greater, repair the open/high resistance in the circuit.

  16. If less than 2 Ω , verify the fuse is not open and there is voltage at the fuse.

    17. [/ARW-LISTFAIL] [ARW-LISTFAIL]

  17. If the test lamp does not illuminate and the circuit fuse is open

    18. [/ARW-LISTFAIL]
    5.1. Ignition OFF.
    5.2. Test for infinite resistance between the B+ circuit connector terminal 6 X1 and ground.
    [ARW-LISTFAIL]

  18. If less than infinite resistance, repair the short to ground in the circuit.

    19. [/ARW-LISTFAIL][ARW-LISTPASS]

  19. If infinite resistance

    20. [/ARW-LISTPASS]
    5.3. Disconnect the harness connector at the M8 Blower Motor.
    5.4. Test for infinite resistance between the B+ circuit connector terminal A and ground.
    [ARW-LISTFAIL]

  20. If less than infinite resistance, repair the short to ground in the circuit.

  21. If infinite resistance, replace K8 Blower Motor Control Module.

    22. [/ARW-LISTFAIL][ARW-LISTPASS]

  22. If the test lamp does illuminate

    23. [/ARW-LISTPASS]
  23. Connect the harness connector X1 to the K8 Blower Motor Control Module.

    24. Note: If test step 7 and 8 are to be repeated for any reason, the ignition must be turned OFF for at least 2 minutes before repeating test.

  24. Ignition ON. Set HVAC Controls to Defrost Mode, Operate the Blower Motor Switch steadily increasing through all steps from OFF to HIGH.
  25. Verify a test lamp increasingly illuminates progressing with blower speed selection between the control circuit connector terminal B and B+ circuit terminal A.
    26. [ARW-LISTFAIL]

  26. If the test lamp is always OFF

    27. [/ARW-LISTFAIL]
    8.1. Ignition OFF. Disconnect the harness connector X2 at the K8 Blower Motor Control Module.
    8.2. Ignition ON Test for less than 1 V between the control circuit terminal B and ground.
    [ARW-LISTFAIL]

  27. If 1 V or greater

    Repair the short to voltage in the circuit.

    28. [/ARW-LISTFAIL][ARW-LISTPASS]

  28. If less than 1 V

    29. [/ARW-LISTPASS]
    8.3. Ignition OFF.
    8.4. Test for infinite resistance between the control circuit terminal B and ground.
    [ARW-LISTFAIL]

  29. If less than infinite resistance, repair the short to ground in the circuit.

    30. [/ARW-LISTFAIL][ARW-LISTPASS]

  30. If infinite resistance

    31. [/ARW-LISTPASS]
    8.5. Test for less than 2 Ω in the control circuit end to end.
    [ARW-LISTFAIL]

  31. If 2 Ω or greater, repair the open/high resistance in the circuit.

  32. If less than 2 Ω, replace the K8 Blower Motor Control Module.

    33. [/ARW-LISTFAIL] [ARW-LISTFAIL]

  33. If the test lamp is always ON

    34. [/ARW-LISTFAIL]
  34. Ignition OFF. Disconnect the harness connector X2 at the K8 Blower Motor Control Module.
  35. Test for infinite resistance between the control circuit terminal B and ground.
    36. [ARW-LISTFAIL]

  36. If less than infinite resistance, repair the short to ground in the circuit.

  37. If infinite resistance, replace the K8 Blower Motor Control Module.

    38. [/ARW-LISTFAIL][ARW-LISTPASS]

  38. If the test lamp does illuminate increasingly

    39. [/ARW-LISTPASS]
  39. Replace the M8 Blower Motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heater and Air Conditioning Control Replacement
    •  Blower Motor Replacement
    •  Heater and Blower and Air Conditioning Control Module Replacement
    •  Control Module References
   


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