| 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
Power for the fan motors is supplied through the
Underhood Accessory Wiring Junction Block, Label
.
The cooling fan relays are energized when current flows from the Cool Fan
1 MaxiFuse® and Cool Fan 2 MaxiFuse® in the
Underhood Accessory Wiring Junction Block, Label
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 Cool Fan 1 Relay. This closes Cool Fan 1 Relay contacts, allowing current
to flow from the
Underhood Accessory Wiring Junction Block, Label
through the relay contacts
to the Engine Coolant Fan Motor 1 (LH). During low speed operation,
the ground path for the Engine Coolant Fan Motor 1 (LH) is through the Cool
Fan 2 Relay and the Engine Coolant Fan Motor 2 (RH). The result is
a series circuit with both cooling fans running at low speed.
During high speed cooling fan operation the PCM supplies a ground path
for the Cool Fan 1 Relay. The PCM also supplies a ground path for Cool Fan
2 and Cool Fan 3 Relays. This closes all three cooling fan relays.
During high speed fans operation, both the Engine Coolant Fan Motor
1 (LH) and the Engine Coolant Fan Motor 2 (RH) are supplied current from
the
Underhood Accessory Wiring Junction Block, Label
and each cooling fan has its own ground path.
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 the following areas:
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. Go 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 Cooling Fan table #1 | ||
4 | With a scan tool, command Low Speed Fans on. Are both cooling fans on? | -- | Go to 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 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 .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 Cool Fan 1 relay. Are both fans OFF? | -- | ||
3 | Disconnect Cool Fan 2 relay. Are both fans OFF? | -- | ||
4 |
Does the test lamp illuminate? | -- | ||
5 | Probe terminal A of the Engine Coolant Fan Motor 1 (LH) connector using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
6 | Probe the High Speed Fans Control circuit (473) at the Cool Fan 2 Relay connector location (85) 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 Low Speed Fans Control circuit (335) at the Cool Fan 1 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 | Repair the RH fan feed circuit (504) for a short to voltage. Refer to Wiring Repairs in Wiring Systems. 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. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
12 | Repair the short to voltage in the Cool Fan 2 Relayswitch feed circuit (532). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
13 | Replace the cool fan 1 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. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
15 | Replace the cool fan 3 relay. Did you complete the repair? | -- | Go to Cooling Fan 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 Cooling Fan Functional Check | -- |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan 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 relay #1 connector locations (86 and 87) using a test lamp that is connected to a good 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 Cool Fan 1 Relay switch feed circuit and the LH fan feed circuit (409) at the relay #1 connector locations (87 and 30). Do both fans turn ON? | -- | ||||||||
7 |
Does the test lamp illuminate? | -- | ||||||||
8 | Connect a second fused jumper wire between the fan harness connector terminals. Is the Engine Coolant Fan Motor 2 (RH) ON? | -- | ||||||||
9 |
Does the test lamp illuminate? | -- | ||||||||
10 | Using a second jumper wire, jumper the switch ignition feed circuit (532) and the RH fan feed circuit (504) together at relay #2 connector locations (30 and 87A). Do the fans come ON? | -- | ||||||||
11 |
Is the Engine Coolant Fan Motor 1 (LH) ON? | -- | ||||||||
12 |
Is the test lamp illuminated? | -- | ||||||||
13 | Inspect the Engine Coolant Fan Motor ground circuits for an open or the Engine Coolant Fan Motor connections and repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections , Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Electric Cooling Fan Functional Check | |||||||
14 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
15 | Repair the RH fan feed circuit (504) for an open or short to ground and replace fuse if necessary.Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | |||||||
16 | Replace Cool Fan 3 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
17 | Repair the relay #2 switch feed circuit (532) for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Electric Cooling Fan Functional Check | |||||||
18 | Replace the fan motor. Refer to Engine Coolant Fan Motor Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
19 | Replace Cool Fan 1 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
20 | Repair the LH fan feed circuit (409) for a open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
21 | Repair the relay #2 switch feed circuit (532) for a open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
22 | Replace Cool Fan 2 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Functional Check | -- |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Functional Check | |
2 |
Did both fans operate with no change? | -- | ||
3 | Did the Engine Coolant Fan Motor 1 (LH) stop operating? | -- | ||
4 |
Does the test lamp illuminate after several seconds? | -- | ||
5 | Probe the coil feed circuit at relay #3 connector location (85) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
6 | Probe the switch feed circuit (2140) at the relay #3 connector location (30) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
7 | Jumper the switch ignition feed circuit (2140) and the RH fan feed circuit (504) together at the relay #3 connector locations (30 and 87). Is the Engine Coolant Fan Motor 2 (RH) ON? | -- | ||
8 |
Do the fans switch from low to high speed? | -- | ||
9 |
Does the test lamp illuminate? | -- | ||
10 | Probe the ground circuit (1050) at the relay #2 connector location (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 relay #2 connector location (86) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
12 | Repair
the Cool Fan 2 Relay and Cool Fan 3 Relay control circuit (473) for an open
between Cool Fan 3 Relay and the splice or replace the
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
13 | Repair
the open in the relay #3 coil feed circuit or replace the
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
14 | Repair
the open or short to ground in the relay #3 switch feed circuit (2140) or
replace the
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
15 | Replace the Cool Fan 3 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Functional Check | -- |
16 | Repair
the open in the RH fan feed circuit (504) between Cool Fan 3 Relay and the
splice or replace the
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
17 | Repair
the fan 2 and 3 relay control circuit (473) for an open or for a short to
battery positive voltage or replace the
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
18 | Repair
the open in the fan 2 and 3 relay control circuit (473) between fan relay
#2 and the splice or replace the
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
19 | Repair the open in the ground circuit (1050). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
20 | Replace the Cool Fan 2 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Functional Check | -- |
21 | Repair
the open in relay #2 coil feed circuit or replace the
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
22 |
Did you find and correct the condition? | -- | Go to Electric Cooling Fan 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 Functional Check | -- |
