• 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.

For symptom byte information refer to Symptom Byte List.

The blower motor speed control signal from the HVAC control module, battery positive and ground circuits enable the blower motor to operate. The blower motor control circuitry is integrated within the blower motor assembly. The HVAC control module provides a ground pulse width modulation (PWM) signal to the blower motor to request a specific motor speed. The blower motor translates the PWM signal and drives the motor accordingly.

• Ignition ON.
• The HVAC control module is ON.

The voltage at the HVAC control module output to the blower motor control module is always high.

The voltage at the HVAC control module output to the blower motor control module is always low or fluctuating.

The blower motor is inoperative.

The condition for setting the DTC is no longer present.

The design of this motor does not allow for bench testing. The motor will not operate by simply applying power and ground.

Inspect the motor shaft for rust or other foreign material which may prohibit proper motor operation.

Check for Preliminary Information or Technical Service Bulletins.

HVAC Schematics

Master Electrical Component List

Manual HVAC Description and Operation

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

Control Module References for scan tool information

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M8 Blower Motor. It may take up to 10 min for all vehicle systems to power down.
2. Test for less than 10 Ω between the ground circuit terminal 6 and ground.
• If 10 Ω or greater
1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, repair the open/high resistance in the ground connection.
• If less than 10 Ω
3. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the test lamp.
2. Test for less than 2 Ω in the B+ circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the test lamp.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the M8 Blower Motor.
• If the test lamp illuminates
4. Remove the test lamp.
5. Ignition ON. Test for less than 1 V between the control circuit terminal 2 and ground.
• If 1 V or greater
1. Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module. Ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K33 HVAC Control Module
• If less than 1 V
6. Ignition OFF. It may take up to 10 min for all vehicle systems to power down.
7. Test for infinite resistance between the control circuit terminal 2 and ground.
• If less than infinite resistance
1. Disconnect the X2 harness connector at the K33 HVAC Control Module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K33 HVAC Control Module
• If infinite resistance

Note: Verify the ignition is OFF before connecting the blower motor or incorrect test results may occur.

8. Ignition OFF, connect the harness connector at the M8 Blower Motor. Ignition ON.
9. While backprobing terminal 2 at the M8 Blower Motor, test for greater than 1 V between control circuit and ground.
• If less than 1 V

  Replace the M8 Blower Motor.

• If 1 V or greater
10. Verify the voltage decreases and increases while using the controls to change the blower speed selection.
• If the voltage does not decrease and increase as the blower speed selection is changed
1. Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module.
2. Test for less than 2 Ω in the control circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K33 HVAC Control Module.
• If the voltage decreases and increases as the blower speed selection is changed
11. Replace the M8 Blower Motor.

Perform the Diagnostic Repair Verification after completing the repair.

• HVAC Component Replacement Reference
• Control Module References for control module replacement, programming and setup