| Table 1: | Electric Cooling Fan Functional Check |
| Table 2: | Electric Cooling Fan Table #1 |
| Table 3: | Electric Cooling Fan Table #2 |
| Table 4: | Electric Cooling Fan Table #3 |
Refer to Engine Controls Schematics .
Circuit Description
The power for the cooling fan motors is supplied through the
Underhood Junction Block
. The
cooling fan relays are energized when current flows from the cool
fan #1 fuse and cool fan #2 fuse in the
Underhood Junction Block
through the relay coils to ground through
the Powertrain Control Module (PCM). The low speed fans (Fan 1)
control circuit is grounded for low speed fans operation. The low
speed fans (fan 1) control circuit and the high speed fans (fan 2) control
circuit are both grounded through the PCM for high speed fans operation.
During low speed fans operation the PCM supplies a ground path for
the #1 fan control relay. This closes #1 fan control relay contacts, allowing
current to flow from the
Underhood Junction Block
through the #1 fan control relay
contacts to the LH cooling fan motor. During low speed operation,
the ground path for the LH cooling fan motor is through the mode control
relay and the RH cooling fan motor to the
Left Side of Engine
During high speed cooling fan operation the PCM supplies a ground path
for the #1 fan control relay. The PCM also supplies a ground path for mode
control relay and the #2 fan control relay. This closes all three cooling
fan relays. During high speed fans operation, both the LH cooling
fan motor and the RH cooling fan motor are supplied current from the
Underhood Junction Block
and
each cooling fan has its own ground path through the
Left Side of Engine
Diagnostic Aids
If the owner complained of an overheating problem, determine if the complaint was due to an actual boil over, or the warning indicator illuminated, or the engine coolant temperature gauge indicated overheating. The gauge accuracy can also be inspected by comparing the ECT sensor reading using a scan tool and comparing its reading with the gauge reading. If the engine is actually overheating and the gauge indicated overheating, but the cooling fans are not turning on, the ECT sensor may have shifted out of calibration and should be replaced. If the engine is overheating and the cooling fans are on, the cooling system is suspect and should be inspected. Refer to Engine Overheating in Engine Cooling.
Inspect for the following conditions:
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to numbers on the diagnostic table.
-
The PCM will enable the engine cooling fans when certain diagnostic trouble codes are set. Refer to applicable DTC table first before proceeding with this table.
-
Allow engine coolant temperature to cool below 100°C (212°F) before proceeding with diagnosis.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain OBD System Check? | -- | ||
Are any DTCs set? | -- | Go to applicable DTCs | ||
Are the cooling fans OFF? | 100°C-(212°F) | Go to Electric Cooling Fan Diagnosis Cooling Fan table #1 | ||
4 | With a scan tool, command low speed fans ON. Are both cooling fans ON? | -- | Go to Electric Cooling Fan Diagnosis Cooling Fan table #2 | |
5 |
Important: : Allow a 3-5 second delay before determining if the fans have switched from low to high speed. With a scan tool, command high speed fans on. Do both cooling fans switch to high speed? | -- | Go to Electric Cooling Fan Diagnosis Cooling Fan table #3 | |
6 |
Are the cooling fans ON? | -- | ||
7 | Turn ON the A/C. Are the cooling fans ON? | -- | System OK | |
8 | Does the scan tool display A/C request as YES? | -- | Go to Cooling Insufficient - Air Conditioning (A/C) System in Heating, Ventilation and Air Conditioning | |
9 | Does the scan tool display A/C request as YES? | -- | Go to Air Conditioning (A/C) Compressor Control Circuit Diagnosis | Go to Cooling Insufficient - Air Conditioning (A/C) System in Heating, Ventilation and Air Conditioning |
10 |
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .Is the action complete? | -- | System OK | -- |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Cooling Fan Functional Check | |
2 | Disconnect #1 Fan Control Relay. Are both fans OFF? | -- | ||
3 | Disconnect Mode Control Relay. Are both fans OFF? | -- | ||
4 |
Does the test lamp illuminate? | -- | ||
5 | Probe terminal A of the left fan connector using a test lamp that is connected to ground. Does the test lamp illuminate? | -- | ||
6 | Probe the High Speed Fans control circuit (473) at the #2 Fan Control
Relay connector in the
Does the test lamp illuminate? | -- | ||
7 |
Is the test lamp still illuminated? | -- | ||
8 | Probe the Low Speed Fans Control circuit (335) at the Cool Fan 1 Relay connector using the test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||
9 |
Is the test lamp still illuminated? | -- | ||
10 | Test the RH fan feed circuit (532) for a short to voltage.
Refer to
Wiring Repairs
in Wiring
Systems. The short may be in the
Did you find and correct the condition? | -- | Go to Cooling Fan Functional Check | |
11 | Repair
the LH fan feed circuit (409) for a short to voltage. Refer to
Wiring Repairs
in Wiring Systems. The short may
be in the
Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
12 | Repair
the short to voltage in the Mode Control Relay feed circuit (504). Refer to
Wiring Repairs
in Wiring Systems. The short may
be in the
Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
13 | Replace the #1 Fan Control Relay. Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
14 | Repair
the High Speed Fans Control circuit (473) or the Low Speed Fans Control circuit
(335) for a short to ground. Refer to
Wiring Repairs
in Wiring Systems. The short may be in the
Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
15 | Replace the #2 Fan Control Relay. Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
16 |
Important: : Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
2 | Did either fan turn ON when the Low Speed Fans were commanded ON? | -- | ||
3 |
Did the other fan turn OFF? | -- | ||
4 | Disconnect Mode Control Relay. Did the fan turn OFF? | -- | ||
5 |
Does the test lamp illuminate? | -- | ||
6 | Probe both feed circuits (440 and 742) at the #1 Fan Control Relay Connector locations using a test lamp that is connected to ground. Does test lamp illuminate for both circuits? | -- | ||
7 |
Important: : Leave jumper in place for remainder of this table. Connect a fused jumper wire between the switch feed circuit (742) and the LH fan feed circuit (409) at the #1 Fan Control Relay Connector locations. Do both fans turn ON? | -- | ||
8 |
Does the test lamp illuminate? | -- | ||
9 | Connect a second fused jumper wire between the right fan harness connector terminals. Is the left fan ON? | -- | ||
10 |
Does the test lamp illuminate? | -- | ||
11 | Using the second jumper wire, jumper the switch feed circuit (504) and the LH fan feed circuit (409) together at the Mode Control Relay connector. Do the fans come ON? | -- | ||
12 |
Is the left fan ON? | -- | ||
13 |
Is the test lamp ON? | -- | ||
14 | Inspect the PCM connections. Refer to Testing for Intermittent Conditions and Poor Connections , and Connector Repairs in Wiring Systems. Did you find a problem and correct the problem? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
15 | Repair the Fan 1 Control circuit (335) for an open or shorted
to battery positive voltage. Refer to
Wiring Repairs
in Wiring Systems. The open/short may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
16 | Inspect the fan motor ground circuit for an open or the
left fan motor connections and repair as necessary. Refer to
Testing for Intermittent Conditions and Poor Connections
and
Connector Repairs
or
Wiring Repairs
in Wiring Systems. The open may
be in the
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
17 | Replace the left fan motor. Refer to Engine Cooling Fan Description - Electric in Engine Cooling. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
18 | Repair the RH fan feed circuit (504 or 532) for an open
or poor connections in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
19 | Replace the fan which was not operating. Refer to Engine Cooling Fan Description - Electric in Engine Cooling. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
20 | Replace #2 Fan Control Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
21 | Repair the Mode Control Relay switch feed circuit (504)
for a short to ground. Refer to
Wiring Repairs
in Wiring Systems. The short may be in the
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
22 | Repair the open or the grounded circuit for the circuit
that did not light. Refer to
Wiring Repairs
in Wiring Systems. The open/short may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
23 | Replace #1 Fan Control Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
24 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
25 | Repair the Mode Control Relay switch feed circuit (504)
for an open, or poor connections at the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
26 | Replace Mode Control Relay . Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
27 |
Important: : Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
2 |
Did both fans operate with no change? | -- | ||
3 | Did the left fan stop operating? | -- | ||
4 |
Does the test lamp illuminate after several seconds? | -- | ||
5 | Probe the coil feed circuit (440) at Mode Control Relay connector using a test lamp that is connected to ground. Does the test lamp illuminate? | -- | ||
6 | Probe the switch feed circuit (2340) at the #2 Fan Control Relay connector using a test lamp that is connected to ground. Does the test lamp illuminate? | -- | ||
7 | Jumper the switch feed circuit (440) and the RH fan feed circuit (532) together at the #2 Fan Control Relay connector. Is the right fan ON? | -- | ||
8 |
Do the fans switch from low to high speed? | -- | ||
9 |
Does the test lamp illuminate? | -- | ||
10 | Probe the ground circuit (450) at the Mode Control Relay connector using a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||
11 | Probe the coil feed circuit (440) at the Mode Control Relay connector using a test lamp that is connected to ground. Does the test lamp illuminate? | -- | ||
12 | Repair the Fan 2 Control circuit (473) for an open between
#2 Fan Control Relay and the splice. Refer to
Wiring Repairs
in Wiring Systems. The open may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
13 | Repair the open in the #2 Fan Control Relay coil feed circuit
(440). Replace the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
14 | Repair the open or poor connections in the #2 Fan Control
Relay switch feed circuit (2340). Replace the
Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
15 | Replace #2 Fan Control Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
16 | Repair the open in the RH fan feed circuit (532) between
#2 Fan Control Relay and the splice. Refer to
Wiring Repairs
in Wiring Systems. The open may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
17 | Repair the Fan 2 Control circuit (473) for an open or for
a short to battery positive voltage. Refer to
Wiring Repairs
in Wiring Systems. The open/short may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
18 | Repair the open in the Fan 2 Control circuit (473) between
Mode Control Relay and the splice. Refer to
Wiring Repairs
in Wiring Systems. The open may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
19 | Repair the open in the ground circuit (450). Refer to
Wiring Repairs
in Wiring Systems. The open may
be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
20 | Replace the #2 Fan Control Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
21 | Repair the open in Mode Control Relay coil feed circuit
(440). Replace the
Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
22 | Inspect for poor connections at the PCM and the
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
23 |
Important: : Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
