Buick Regal: Cooling Fan Inoperative (LTG)

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.

Circuit/System Description

The engine cooling fan system is composed of one electric cooling fan and a cooling fan control module.

The engine control module (ECM) controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal, which enables cooling fan operation at variable speeds. The ECM will only operate the cooling fan at certain percentages to prevent undesirable noise and vibration. The cooling fan control module is thermally protected to prevent module damage in the case of a short circuit condition in the cooling fan motor.

Diagnostic Aids

• The cooling fan will not operate when the scan tool Cooling Fan Motor Command parameter displays less than 4 %. This is a normal condition.
• A delay or ramp up of approximately 12 seconds may occur before the cooling fan activates or changes speed when being commanded with a scan tool.
• The cooling fan Control Function operates as described below when the ignition is ON, and engine is OFF:
  • Command State 1 operates the cooling fan at approximately 18 %
  • Command State 2 operates the cooling fan at approximately 54 %
  • Command State 3 operates the cooling fan at approximately 67 %
  • Command State 4 operates the cooling fan at approximately 85 %
  • Command State 5 operates the cooling fan at approximately 90 %
• During normal operating conditions the ECM may initially activate the cooling fan at 4 or 5 % and then increase to the percentages indicated above, as needed, to satisfy powertrain cooling requirements. Generally, the ECM will operate the cooling fan at the specified percentages but, may scale the percentages either higher or lower in response to generator demand.
• When operating the cooling fan with a scan tool, the Commanded States 1 - 5 should be exercised in order, from OFF to High or High to OFF. The cooling fan control module may disable the cooling fan if a Commanded State is skipped.

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

Cooling Fan 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 Verification

1. Ignition ON.

2. Verify that DTC P0480, P0691, or P0692, is not set.

• If a DTC is set

Refer to DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LTG) or DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LGX).

• Go to next step: If no DTC is set.

NOTE: A slight delay may occur before the cooling fan activates.

3. Verify the G10 Cooling Fan Motor activates and increases in speed with each command using a scan tool.

• The cooling fan does not activate or increase in speed

Refer to Circuit/System Testing

• Go to next step: The cooling fan activates and increases in speed

4. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector G10 Cooling Fan Motor.

2. Verify that a test lamp illuminates between the ground circuit terminal 2 and B+.

• If the test lamp does not illuminate

1. Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down.
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 the test lamp illuminates

3. Test or replace the G10 Cooling Fan Motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• Engine Coolant Fan Replacement (2.0L LTG) or Engine Coolant Fan Replacement (3.6L LGX) for G10 Cooling Fan Motor replacement.
• Control Module References

ENGINE OVERHEATING

DEFINITION: Either of the following conditions indicate a probable engine overheat condition. The engine temperature gauge is in the red (overheat) zone and/or the engine temperature indicator is ON. Hot engine coolant overflows from the coolant recovery reservoir and/or radiator cap onto the ground while the engine is running.

LOSS OF COOLANT

THERMOSTAT DIAGNOSIS

COOLANT HEATER INOPERATIVE

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.

Circuit/System Description

The coolant heater is a 300 watt heating element that mounts to the engine block. The coolant heater operates using 120 V AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. The coolant heater also helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. There is an internal thermal switch in the coolant heater cord that prevents operation above -18ºC (0ºF). A weather shield on the cord is provided to protect the plug when not in use.

Reference Information

Electrical Information Reference

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

Circuit/System Testing

NOTE: The coolant heater cord will read Open due to an internal thermal switch if the ambient temperature is above -18ºC (0ºF).

1. Ignition OFF, disconnect the coolant heater cord from the E19 Coolant Heater.

2. Test for 40 - 55 Ω between the terminals of the E19 Coolant Heater.

• If not within 40 - 55 Ω

Replace the E19 Coolant Heater.

• Go to next step: If within 40 - 55 Ω

3. Test for infinite resistance between each terminal of the E19 Coolant Heater and ground.

• If less than infinite resistance

Replace the E19 Coolant Heater.

• Go to next step: If infinite resistance

4. Test for less than 2 Ω between the engine coolant heater cord plug and the engine coolant heater cord connector for each circuit.

• If greater than 2 Ω

Replace the engine coolant heater cord.

• Go to next step: If less than 2 Ω

Go to next step: All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic repair.

ENGINE FAILS TO REACH NORMAL OPERATING TEMPERATURE

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