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

Voltage is supplied to the relay coil from BJB (Battery Junction Box) fuse 23 (5A) and relay switch contacts from BJB (Battery Junction Box) fuse 10 (40A). When the blower motor relay coil receives a ground from the BCM (Body Control Module), the relay coil is energized and voltage is delivered to the blower motor control module. Power and ground for the blower motor is provided by the blower motor speed control. 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. VERIFY THE BLOWER MOTOR OPERATION

1. Ignition ON.

2. Press the panel button on the HVAC (Heating, Ventilation, and Air Conditioning) module. Adjust the blower motor setting to the minimum and maximum settings.

Does the blower motor operate at any setting?






2. CHECK THE BLOWER MOTOR CONTROL CIRCUIT FOR AN OPEN

1. Ignition OFF.

2. Disconnect: Blower Motor Speed Control C297A.

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

4. Measure:





Is the resistance less than 3 ohms?






3. CHECK THE BLOWER MOTOR CONTROL CIRCUIT FOR A SHORT TO GROUND

1. Measure:





Is the resistance greater than 10,000 ohms?






4. CHECK THE BLOWER MOTOR CONTROL CIRCUIT FOR A SHORT TO POWER

1. Measure:





Is any voltage present?






5. CHECK THE BLOWER MOTOR OPERATION WITH THE BLOWER MOTOR RELAY DISCONNECTED

1. Ignition OFF

2. Disconnect: Blower Motor Relay

Does the fan still operate all the time?






6. CHECK THE BLOWER MOTOR RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND

1. Disconnect: BCM (Body Control Module) C2280A.

2. Measure:





Is the resistance greater than 10,000 ohms?






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

1. Ignition OFF.

2. Disconnect and inspect all the 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?






8. CHECK FOR CORRECT BCM (Body Control Module) OPERATION

1. Ignition OFF.

2. Disconnect and inspect all the BCM (Body Control 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 BCM (Body Control 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?