Diagnostic Routine B

Diagnostic Routine B

Diagnostic Overview

The Auxiliary Blower Motor Does Not Operate Correctly

Refer to Wiring Diagram Set 52 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

The auxiliary blower motor relay coil receives a ground from the HVAC (Heating, Ventilation, and Air Conditioning) module. When the relay coil is energized, voltage is delivered from the relay to the auxiliary blower motor speed control and auxiliary blower motor. The auxiliary blower motor speed control is grounded. The HVAC (Heating, Ventilation, and Air Conditioning) module provides a PWM (Pulse Width Modulated) signal to the auxiliary blower motor speed control to control the blower speed. Ground for the motor is provided from the auxiliary blower motor speed control.

DTC Fault Trigger Conditions






Pinpoint Test

1. CHECK THE HVAC (Heating, Ventilation, and Air Conditioning) MODULE FOR DTCs (Diagnostic Trouble Codes)

1. Ignition ON.

2. Using a scan tool, perform the HVAC (Heating, Ventilation, and Air Conditioning) module self-test.

Is DTC (Diagnostic Trouble Code) B10BA:12 present?








2. CHECK THE AUXILIARY BLOWER MOTOR RELAY COIL SWITCH GROUND CIRCUIT FOR A SHORT TO GROUND

1. Ignition OFF.

2. Disconnect: Auxiliary Blower Motor Relay.

3. Disconnect: HVAC (Heating, Ventilation, and Air Conditioning) Module C228B.

4. Measure:





Is the resistance greater than 10,000 ohms?








3. CHECK THE AUXILIARY BLOWER MOTOR VOLTAGE CIRCUIT FOR A SHORT TO VOLTAGE

1. Disconnect: Auxiliary Blower Motor Speed Control.

2. Disconnect: Auxiliary Blower Motor.

3. Ignition ON.

4. Measure:





Is any voltage present?








4. CHECK THE AUXILIARY BLOWER MOTOR GROUND CIRCUIT FOR A SHORT TO GROUND

1. Ignition OFF.

2. Measure:





Is the resistance greater than 10,000 ohms?








5. CHECK THE AUXILIARY BLOWER MOTOR SPEED CONTROL COMMAND CIRCUIT FOR A SHORT TO VOLTAGE

1. Ignition OFF.

2. Disconnect: HVAC (Heating, Ventilation, and Air Conditioning) Module C228B.

3. Disconnect: Auxiliary Blower Motor Speed Control.

4. Ignition ON.

5. Measure:





Is any voltage present?








6. CHECK THE AUXILIARY BLOWER MOTOR SPEED CONTROL

1. Install a known good auxiliary blower motor speed controller.

2. Reconnect all disconnected connectors. Make sure they seat and latch correctly.

3. Ignition ON.

4. Operate the auxiliary blower motor.

Does the auxiliary blower motor function correctly?








7. CHECK FOR CORRECT HVAC (Heating, Ventilation, and Air Conditioning) MODULE OPERATION

1. Ignition OFF.

2. Disconnect and inspect all HVAC (Heating, Ventilation, and Air Conditioning) module connectors.

3. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

4. Reconnect the HVAC (Heating, Ventilation, and Air Conditioning) module connectors. Make sure they seat and latch correctly.

5. Operate the system and determine if the concern is still present.

Is the concern still present?