| 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 Schematic
Cooling Fans
.
Circuit Description
Power for the fan motors is supplied through the underhood junction
block. Refer to Engine Control Components
Underhood Junction Block
. The cooling fan relays are energized when
current flows from the Cool Fan #1 fuse and the Cool Fan #2 fuse in
the underhood junction block through the relay coils to ground through the
powertrain control module (PCM). The LH fan control circuit is grounded
for low speed fans operation. The LH fan control circuit and the
RH fan control circuits are both grounded 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 relay contacts to the LH cooling fan motor. During low speed fans operation, the ground path for the LH cooling fan motor is through the mode control relay and the RH cooling fan motor. The result is a series circuit with both cooling fans running at low speed.
During high speed fans operation the PCM supplies a ground path for
the #1 fan control relay and then the mode control and the #2 fan control
relay. This closes all 3 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 ground splice pack. Refer to Engine
Control Components
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, the warning indicator illuminated, or the engine coolant temperature gauge indicated overheating. The gauge accuracy can also be tested 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.
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 DTCs are set. Refer to applicable DTC table first before proceeding with this table.
-
Allow ECT to cool below 100°C (212°F) before proceeding with diagnosis.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (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 Electric 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 Electric 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 Electric 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 Powertrain Control Module Controlled Air Conditioning (A/C) 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 . Did you complete the replacement? | -- | System OK | -- |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis 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 right fan control circuit (473) at the mode control relay connector location (86) using a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||||||||
7 |
Is the test lamp still illuminated? | -- | ||||||||
8 | Probe the left fan control circuit (335) at the #1 fan control relay connector location (85) using the test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||||||||
9 |
Is the test lamp still illuminated? | -- | ||||||||
10 |
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |||||||
11 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
12 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
13 | Replace the #1 fan control relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
14 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
15 | Replace the #2 fan control relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
16 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |||||||||
2 | Did either fan turn ON when the Low Speed Fans were commanded ON? | -- | ||||||||||
3 |
Did the left fan turn OFF? | -- | ||||||||||
4 |
Does the test lamp illuminate? | -- | ||||||||||
5 | Probe both feed circuits at the #1 fan control relay connector terminals, 30 and 86, using a test lamp that is connected to ground. Does test lamp illuminate for both circuits? | -- | ||||||||||
6 |
Important: Leave jumper in place for remainder of this table. Connect a fused jumper wire between the switch feed circuit and the left fan feed circuit (409) at the #1 fan control relay connector terminals 30 and 87. Do both fans turn ON? | -- | ||||||||||
7 |
Does the test lamp illuminate? | -- | ||||||||||
8 | Connect a second fused jumper wire between the left fan harness connector terminals. Is the right fan ON? | -- | ||||||||||
9 |
Does the test lamp illuminate? | -- | ||||||||||
10 | Using a second jumper wire, jumper the switch feed circuit (504) and the right fan feed circuit (532) together at the mode control relay connector terminals 30 and 87A. Do the fans come ON? | -- | ||||||||||
11 |
Did the test lamp illuminate? | -- | ||||||||||
12 |
Does the test lamp illuminate? | -- | ||||||||||
13 | Inspect the PCM connector for poor and intermittent connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |||||||||
14 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
15 |
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |||||||||
16 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
17 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |||||||||
18 | Replace the fan which was not operating. Refer to Engine Cooling Fan Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
19 | Replace the #2 fan control relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
20 |
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |||||||||
21 | Replace the fan motor. Refer to Engine Cooling Fan Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
22 | Replace the #1 fan control relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
23 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
24 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
25 |
| -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
26 | Replace mode control relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||||
27 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis 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 at #2 fan control relay connector terminal (86) 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 terminal (30) using a test lamp that is connected to ground. Does the test lamp illuminate? | -- | ||||||||
7 | Jumper the switch feed circuit (2340) and the right fan feed circuit (532) together at the #2 fan control relay connector terminals 30 and 87. 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 terminal (87) using a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||||||||
11 | Probe the coil feed circuit at the mode control relay connector Terminal (85) using a test lamp that is connected to a ground. Does the test lamp illuminate? | -- | ||||||||
12 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
13 |
Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
14 |
Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
15 | Replace the #2 fan control relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
16 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
17 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
18 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
19 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
20 | Replace the mode control relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
21 |
Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- | ||||||
22 | Inspect the PCM connector for poor, and intermittent connections. Refer to Testing for Intermittent Conditions and Poor Connections , and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |||||||
23 |
Important : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
