| 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
Coolant Fans
.
Circuit Description
The power for the cooling fan motors is supplied through the
Bottom Underhood Electrical Center, Top View
. The fan 1 relay, the fan 2 relay, and the fan 3
relay are all energized when current flows from the fan 1 25 A
fuse and the fan 2 and 3 25 A fuse in the
Bottom Underhood Electrical Center, Top View
through
the relay coils to ground through the PCM. The low speed fans control
circuit is grounded for low speed fans operation. The low speed fans control
circuit and the high speed fans control circuits are all grounded for high
speed fans operation.
During low speed fans operation the PCM supplies a ground path for
the fan 1 relay. This closes the fan 1 relay contacts, allowing
current to flow from the
Bottom Underhood Electrical Center, Top View
through the relay contacts to the right
cooling fan. During low speed fans operation, the
Front of Vehicle-Forward Lamp Harness
During high speed fans operation the PCM supplies a ground path for
the fan 1 relay through the low speed fans control circuit. The PCM
also supplies a ground path for the fan 2 relay and the fan 3
relay through the high speed fans control circuit. This closes all 3 cooling
fan relays. During high speed fans operation, both the left cooling fan and
the right cooling fan are supplied current from the
Bottom Underhood Electrical Center, Top View
and each
cooling fan has a
Front of Vehicle-Forward Lamp Harness
Diagnostic Aids
If the owner complained of an overheating problem, determine if the complaint was due to an actual boil-over, the malfunction indicator illuminating, or the engine coolant temperature gauge indicating overheating. The gauge accuracy can also be checked by comparing the gauge reading with the engine coolant temperature (ECT) sensor reading on a scan tool. If the engine is 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 checked.
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 the step numbers on the diagnostic table:
-
The PCM will enable the engine cooling fans when certain diagnostic trouble codes are set. Go to the applicable DTC table before proceeding with this table.
-
Allow the engine coolant temperature to cool to less than 100°C (212°F) before proceeding with the diagnosis.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||
Are any other DTCs set? | -- | Go to the applicable DTCs | ||
Are the cooling fans OFF? | 100°C (212°F) | Go to Table 1 in Electric Cooling Fan Diagnosis | ||
4 | With a scan tool, command the Low Speed Fans ON. Do both cooling fans turn ON? | -- | Go to Table 2 in Electric Cooling Fan Diagnosis | |
5 | With a scan tool, command the High Speed Fans ON. Do both cooling fans switch to high speed? | -- | Go to Table 3 in Electric Cooling Fan Diagnosis | |
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 the A/C request as YES? | -- | Go to Cooling Insufficient - Air Conditioning (A/C) System in HVAC Systems-Manual | |
9 |
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 the Functional Check in Electric Cooling Fan Diagnosis | |
2 |
Are both fans OFF? | -- | ||
3 | Disconnect the fan 2 relay. Are both fans OFF? | -- | ||
4 | Remove the fan 3 relay. Are both fans OFF? | -- | ||
5 |
Does the test lamp illuminate? | -- | ||
6 | Probe the feed terminal of the fan 2 relay switch at the right cooling fan connector using a test lamp connected to ground. Does the test lamp illuminate? | -- | ||
7 | Probe the high speed fans control circuit at the fan 2 relay connector using a test lamp connected to B+ voltage. Does the test lamp illuminate? | -- | ||
8 |
Is the test lamp still illuminated? | -- | ||
9 | Probe the low speed fans control circuit at the fan 1 relay connector using a test lamp connected to B+ voltage. Does the test lamp illuminate? | -- | ||
10 |
Is the test lamp still illuminated? | -- | ||
11 | Test the left cooling fan feed circuit for a short to voltage and repair as necessary. Refer to Wiring Repairs in Wiring System. Did you find and correct a condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
12 | Test the right cooling fan feed circuit for a short to voltage and repair as necessary. Refer to Wiring Repairs in Wiring System. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
13 | Repair the short to voltage in the fan 2 relay switch feed circuit. Refer to Wiring Repairs in Wiring System. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
14 | Replace the fan 1 relay. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
15 | Test the control circuits for the high speed fans and the low speed fans for a short to ground. Refer to Wiring Repairs in Wiring System. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
16 | Replace the fan 3 relay. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
17 | Replace the fan 2 relay. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
18 |
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
2 | Does either fan turn ON when the Low Speed Fans are commanded ON? | -- | ||
3 | With a scan tool, command the High Speed Fans ON. Does the inoperative fan from Step 2 turn ON? | -- | ||
4 | Disconnect the fan 3 relay. Does the inoperative fan from Step 2 turn OFF? | |||
5 |
Does the test lamp illuminate? | -- | ||
6 | Probe both feed circuits at the fan 1 relay connector using a test lamp connected to ground. Does test lamp illuminate on both circuits? | -- | ||
7 |
Important: : Leave the jumper in place for the remainder of this table. Connect a 30 amp fused jumper wire between the switch feed circuit and the right cooling fan feed circuit at the fan 1 relay connector. Do both fans turn ON? | -- | ||
8 |
Does the test lamp illuminate? | -- | ||
9 | Connect a second 30 amp fused jumper wire between the right cooling fan harness connector terminals. Does the left cooling fan turn ON? | -- | ||
10 |
Does the test lamp illuminate? | -- | ||
11 | Using the second jumper wire, jumper the switch feed circuit and the left cooling fan feed circuit together at the fan 2 relay connector. Do both fans turn ON? | -- | ||
12 |
Does the test lamp illuminate? | -- | ||
13 |
Does the test lamp illuminate? | -- | ||
14 | Inspect for faulty connections at the PCM and at the harness connectors and repair as necessary. Refer to Wiring Repairs in Wiring System. Did you find a problem and correct the condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
15 | Inspect the low speed fans control circuit for an open or a short to battery positive voltage. Refer to Wiring Repairs in Wiring System. Did you find and correct a condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
16 | Inspect the fan motor ground circuit for an open or any poor connections. Refer to the following in Wiring Systems: Did you find and correct the condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
17 | Inspect the fan motor and the harness connectors for faulty terminals and replace as necessary. Refer to Connector Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
18 | Replace the fan motor. Refer to Fan Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
19 | Test the left cooling fan feed circuit for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
20 | Test the supply circuit to the inoperative fan for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
21 | Replace the fan that is not operating. Refer to Fan Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
22 | Replace the fan 3 relay. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
23 | Test the fan 2 relay switch feed circuit for a short to ground Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
24 |
Important: : If the fuse is open, locate and repair a short to ground on the load circuit or a shorted component. Repair the open or the grounded circuit for the circuit that did not illuminate the test lamp. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
25 | Inspect the fan 1 relay and the connector for faulty terminals. Refer to Connector Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
26 | Replace the fan 1 relay. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
27 | Test the right cooling fan feed circuit for an open and repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
28 | Test the fan 2 relay switch feed circuit for an open and repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
29 | Inspect the fan 2 relay and the connector for faulty terminals. Refer to Connector Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
30 | Replace the fan 2 relay. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
31 |
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
2 |
Did both fans operate with no change? | -- | ||
3 | Did the right cooling fan stop operating? | -- | ||
4 |
Does the test lamp illuminate after a few seconds? | -- | ||
5 | Probe the coil feed circuit at the fan 3 relay connector using a test lamp connected to ground. Does the test lamp illuminate? | -- | ||
6 | Probe the switch feed circuit at the fan 3 relay connector using a test lamp connected to ground. Does the test lamp illuminate? | -- | ||
7 | Install a 30 amp fused jumper between the switch feed circuit and the left cooling fan feed circuit at the fan 3 relay connector. Does the left cooling fan turn ON? | -- | ||
8 |
Do the fans switch from low speed to high speed? | -- | ||
9 |
Does the test lamp illuminate after a few seconds? | -- | ||
10 | Probe the ground circuit at the fan 2 relay connector using a test lamp connected to B+ voltage. Does the test lamp illuminate? | -- | ||
11 | Probe the coil feed circuit at the fan 2 relay connector using a test lamp connected to ground. Does the test lamp illuminate? | -- | ||
12 | Repair the high speed fans control circuit for an open between the fan 3 relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
13 | Repair the open in the fan 3 relay coil feed circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
14 |
Important: : If the fuse is open, locate and repair a short to ground on the load circuit or a shorted component. Repair the open in the fan 3 relay switch feed circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
15 | Replace the fan 3 relay. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
16 | Repair the open in the left cooling fan feed circuit between the fan 3 relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
17 | Repair the high speed fans control circuit for an open or a short to B+ voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
18 | Repair the open in the high speed fans control circuit between the fan 2 relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
19 | Repair the open in the ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
20 | Replace the fan 2 relay. Did you complete the replacement? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
21 |
Important: : If the fuse is open, locate and repair a short to ground on the load circuit or a shorted component. Repair the open in the fan 2 relay coil feed circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | -- |
22 | Inspect the PCM connections. Refer to Connector Repairs and to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to the Functional Check in Electric Cooling Fan Diagnosis | |
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 the Functional Check in Electric Cooling Fan Diagnosis | -- |
