Buick Regal: DTC B0193

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.

DTC Descriptors

DTC B0193 01

Front Blower Motor Speed Circuit Short to Battery

DTC B0193 06

Front Blower Motor Speed Circuit Low Voltage/Open

Diagnostic Fault Information

Circuit/System Description

The blower motor control module is an interface between the HVAC control module and the blower motor. The blower motor control module has 5 circuits: a B+ input, ground, a control circuit from the HVAC control module, a B+ output to the blower motor, and a low side pulse width modulation (PWM) output. The HVAC control module provides a low side (PWM) signal to the blower motor control module in order to request the blower motor speed. The blower motor control module grounds the blower motor using a low side PWM signal in order to vary the blower motor speed.

Conditions for Running the DTC

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

Conditions for Setting the DTC

B0193 01

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

B0193 06

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

Action Taken When the DTC Sets

The blower motor is inoperative.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Diagnostic Aids

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

If the motor operates properly please reinstall it and check for Preliminary Information or Technical Service Bulletins.

Reference Information

Schematic Reference

HVAC Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

Automatic HVAC Description and Operation

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 Testing

1. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the K8 Blower Motor Control Module. 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 5 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.

• Go to next step: If less than 10 Ω

3. Verify a test lamp illuminates between the B+ circuit terminal 6 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 terminal 6 and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Disconnect the X2 harness connector at the K8 Blower Motor Control Module and disconnect the harness connector at the M8 Blower Motor.
4. Test for infinite resistance between the M8 Blower Motor B+ circuit terminal B and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • If infinite resistance, test or replace the M8 Blower Motor.

• Go to next step: If the test lamp illuminates

4. Ignition ON. Test for less than 1 V between the control circuit terminal 3 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

• Go to next step: If less than 1 V

5. Ignition OFF. It may take up to 10 min for all vehicle systems to power down.

6. Test for infinite resistance between the control circuit terminal 3 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

• Go to next step: If infinite resistance

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

7. Ignition OFF, connect the X1 harness connector at the K8 Blower Motor Control Module. Ignition ON.

8. While backprobing terminal 3 at the K8 Blower Motor Control Module, test for greater than 1 V between the control circuit and ground.

• If less than 1 V

Replace the K8 Blower Motor Control Module.

• Go to next step: If 1 V or greater

9. 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.

• Go to next step: If the voltage decreases and increases as the blower speed selection is changed

10. Ignition OFF, disconnect the harness connector at the M8 Blower Motor, ignition ON and blower ON.

11. Verify a test lamp illuminates between the B+ circuit terminal B and ground.

• If the test lamp does not illuminate

1. Ignition OFF, disconnect the X2 harness connector at the K8 Blower Motor 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 K8 Blower Motor Control Module.

• Go to next step: If the test lamp illuminates

12. Connect a test lamp between control circuit terminal A and B+ circuit terminal B.

13. Verify the test lamp becomes progressively brighter as the blower speed is increased and progressively dimmer as the blower speed is decreased.

• If the test lamp does not illuminate

1. Ignition OFF, disconnect the X2 harness connector at the K8 Blower Motor Control Module, ignition ON.
2. Test for less than 1 V between the control circuit terminal 1 and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • Go to next step: If less than 1 V
3. 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 K8 Blower Motor Control Module.

• If the test lamp illuminates, but does not change in brightness

1. Ignition OFF, disconnect the X2 harness connector at the K8 Blower Motor 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 K8 Blower Motor Control Module.

• Go to next step: If the test lamp changes in brightness as the blower speed is changed

14. Test or replace the M8 Blower Motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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

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