Buick Regal: Cooling Fan Inoperative (LGX)
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 two electric cooling fans and a
cooling fan control module.
The engine control module (ECM) controls the fan speeds 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 motors in relation to the pulse width modulated signal, which
enables cooling fan operations at
variable speeds. The ECM will only operate the cooling fans 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 motors.
Diagnostic Aids
- The cooling fans 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 fans activate or
change speeds 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 fans at approximately 18 %
- Command State 2 operates the cooling fans at approximately 54 %
- Command State 3 operates the cooling fans at approximately 67 %
- Command State 4 operates the cooling fans at approximately 85 %
- Command State 5 operates the cooling fans at approximately 90 %
- During normal operating conditions the ECM may initially activate the
cooling fans 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 fans at the
specified percentages but, may
scale the percentages either higher or lower in response to generator
demand.
- When operating the cooling fans 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
fans 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.
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 Motors activate and increases in speed with
each command using a scan
tool.
- The cooling fans do not activate or increase in speed
Refer to Circuit/System Testing
- Go to next step: The cooling fans activate and increases in speed
4. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector G10L Cooling Fan Motor or
G10R Cooling Fan
Motor.
2. Verify that a test lamp illuminates between the ground circuit terminal 2 and
B+ of the inoperative
G10 Cooling Fan Motor.
- If the test lamp does not illuminate
- Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes
for all vehicle systems
to power down.
- 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 inoperative 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
READ NEXT:
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.
Diag
Special Tools
GE-42401-A Radiator Cap and Surge Tank Test Adapter
For equivalent regional tools, refer to Special Tools.
WARNING: To avoid being burned, do not remove the radiator cap or surge
tank
c
Special Tools
GE-42401-A Radiator Cap and Surge Tank Test Adapter
For equivalent regional tools, refer to Special Tools.
WARNING: Under pressure, the temperature of the solution in the
radiator can b
SEE MORE:
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
D
System Overview
The engine cooling fan system consists of 2 electric cooling fans and 3 fan
relays. The cooling fan relays
are arranged in a series/parallel (S/P) configuration. This allows the engine
control module (ECM) to
operate both fans together at low or high speeds using 2 fan control circ