Diagnostic Routine S

Diagnostic Routine S

Diagnostic Overview

The Blower Motor Does Not Operate Correctly

Refer to Wiring Diagram Set 55 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

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

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) B10B9:12 present?








2. CHECK THE BLOWER MOTOR OPERATION USING ACTIVE COMMANDS

1. Using a scan tool, view HVAC (Heating, Ventilation, and Air Conditioning) Module PIDs (Parameter Identifications).

2. Select panel mode on the HVAC (Heating, Ventilation, and Air Conditioning) controls.

3. Select the lowest blower motor setting.

4. Monitor blower motor speed while using the scan tool to operate the HVAC (Heating, Ventilation, and Air Conditioning) module active command BLOWRSPD, increasing and decreasing the percentage value.

Does the blower motor speed change between low and high when the active command is changed?








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

1. Ignition OFF.

2. Disconnect: Blower Motor Relay.

3. Disconnect: HVAC (Heating, Ventilation, and Air Conditioning) Module C228A.

4. Measure:





Is the resistance greater than 10,000 ohms?








4. CHECK THE BLOWER MOTOR VOLTAGE CIRCUIT FOR A SHORT TO VOLTAGE

1. Disconnect: Blower Motor.

2. Ignition ON.

3. Measure:





Is any voltage present?








5. CHECK FOR VOLTAGE AT THE BLOWER MOTOR WITH THE BLOWER MOTOR RELAY DISCONNECTED

1. Disconnect: Blower Motor Relay.

2. Ignition ON.

3. Measure:





Is any voltage present?








6. CHECK THE BLOWER MOTOR SPEED CONTROLLER FUNCTIONALITY

1. Install a known good blower motor speed controller.

2. Ignition ON.

3. Operate the blower motor.

Does the blower motor function correctly?








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

1. Ignition OFF.

2. Disconnect: Blower Motor Speed Control.

3. Disconnect: HVAC (Heating, Ventilation, and Air Conditioning) Module C228A.

4. Ignition ON.

5. Measure:





Is any voltage present?








8. 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?