| 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
Engine Wiring Harness Junction Block 1 (Label)
and
Engine Wiring Harness Junction Block 2 Label
. The cooling fan relays are energized when current flows from the
MaxiFuse® 1 in the
Engine Wiring Harness Junction Block 1 (Label)
and Fan 3 Fuse in the
Engine Wiring Harness Junction Block 2 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 Fan Cont #1 Relay. This closes Fan Cont #1 Relay contacts, allowing current
to flow from the
Engine Wiring Harness Junction Block 1 (Label)
through the relay
contacts to the Engine Coolant Fan Motor 1. During low speed
operation, the ground path for the Engine Coolant Fan Motor 1 is through
the Fan Cont #2 Relay and the Engine Coolant Fan Motor 2. 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 Fan Cont #1 Relay. The PCM also supplies a ground path for Fan Cont
#2 Relay and Fan 3 Relay. This closes all three cooling fan relays.
During high speed fans operation, both the right and the left hand
engine cooling fans are supplied current from the
Engine Wiring Harness Junction Block 1 (Label)
and
Engine Wiring Harness Junction Block 2 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, 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.
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 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 | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Are any DTCs set? | -- | Go to the applicable DTC table | ||
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 in HVAC | 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 | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
2 |
Are both fans OFF? | -- | ||
3 | Disconnect the Fan Cont #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 Fan Cont #2 Relay switch feed terminal at the Engine Coolant Fan Motor 1 connector using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
7 | Probe the High Speed Fans Control circuit at the Fan Cont #2 Relay connector using a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||
8 |
Is the test lamp still illuminated? | -- | ||
9 | Probe the Low Speed Fans Control circuit at the Fan Cont #1 Relay connector using a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||
10 |
Is the test lamp still illuminated? | -- | ||
11 | Test the
Engine Coolant Fan Motor 1 feed circuit for a short to voltage and repair
as necessary. Refer to
Wiring Repairs
in Wiring System. The short may be in the
Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
12 | Test the Engine Coolant Fan Motor 2 feed circuit for a short to voltage.
Refer to
Wiring Repairs
in Wiring
System. The short may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
13 | Repair
the short to voltage in the Fan Cont #2 Relay switch feed circuit. Refer
to
Wiring Repairs
in Wiring System.
The short may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
14 | Replace the Fan Cont #1 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
15 | Test the
High Speed Fans Control circuit or the Low Speed Fans Control circuit for
a short to ground. Refer to
Wiring Repairs
in Wiring System. The short may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
16 | Replace the Fan #3 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
17 | Replace the Fan Cont #2 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
18 |
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 | Value(s) | 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 was commanded ON? | -- | ||
3 | With a scan tool, command the High Speed Fans ON. Did the inoperative fan from step 2 turn ON? | -- | ||
4 | Disconnect the Fan #3 Relay. Did the inoperative fan from step 2 turn OFF? | |||
5 |
Does the test lamp illuminate? | -- | ||
6 | Probe both feed circuits at the Fan Cont #1 Relay connector using a test lamp that is connected to ground. Does test lamp illuminate for 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 Engine Coolant Fan Motor 1 feed circuit at the Fan Cont #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 Engine Coolant Fan Motor 1 harness connector terminals. Does the Engine Coolant Fan Motor 2 turn ON? | -- | ||
10 |
Does the test lamp illuminate? | -- | ||
11 | Using the second jumper wire, jumper the switch feed circuit and the Engine Coolant Fan Motor 2 feed circuit together at the Fan Cont #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 harness connectors and repair as necessary. Refer to
Wiring Repairs
in Wiring System. The open/poor
connection may be in the
Did you find a problem and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
15 | Inspect the Low Speed Fans Control circuit for an open or short to battery
positive voltage. Refer to
Wiring Repairs
in Wiring System. The open/short connection may be in the
Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
16 | Inspect the fan motor ground circuit for an open or poor connections. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
17 | Inspect the fan motor and harness connectors for faulty terminals and replace as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
18 | Replace the fan motor. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
19 | Test the
Engine Coolant Fan Motor 2 feed circuit for an open. Refer to
Wiring Repairs
in Wiring Systems. The open/poor
connection may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
20 |
Important: : If the fuse is open, locate and repair a short to ground on the load circuit or a shorted component.
Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
21 | Replace the fan which was not operating. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
22 | Replace the Fan #3 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
23 | Inspect the following circuits/components for a short.
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
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. The open/short may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
25 | Inspect
the Fan Cont #1 Relay and connector for faulty terminals. Refer to
Wiring Repairs
in Wiring Systems. The open/poor
connection may be in the
Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
26 | Replace the Fan Cont #1 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
27 | Test the
Engine Coolant Fan Motor 1 feed circuit for an open and repair as necessary.
Refer to
Wiring Repairs
in Wiring Systems.
The open/poor connection may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
28 | Test the
Fan Cont #2 Relay switch feed circuit for an open and repair as necessary.
Refer to
Wiring Repairs
in Wiring Systems.
The open/poor connection may be in the
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
29 | Inspect
the Fan Cont #2 Relay and connector for faulty terminals. Refer to
Wiring Repairs
in Wiring Systems. The open/poor
connection may be in the
Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | |
30 | Replace the Fan Cont #2 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
31 |
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 | Value(s) | 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 Engine Coolant Fan Motor 1 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 that is connected to ground. Does the test lamp illuminate? | -- | ||
6 | Probe the switch feed circuit at the Fan #3 Relay connector using a test lamp that is connected ground. Does the test lamp illuminate? | -- | ||
7 | Install a 30 amp fused jumper between the switch feed circuit and the Engine Coolant Fan Motor 2 feed circuit at the Fan #3 Relay connector. Does the Engine Coolant Fan Motor 2 turn ON? | -- | ||
8 |
Do the fans switch from low to high speed? | -- | ||
9 |
Does the test lamp illuminate after a few seconds? | -- | ||
10 | Probe the ground circuit at the Fan Cont #2 Relay connector using a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||
11 | Probe the coil feed circuit at the Fan Cont #2 Relay connector using a test lamp that is 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
Connector Repairs
,
Testing for Intermittent Conditions and Poor Connections
, and
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 |
Important: : If the fuse is open, locate and repair a short to ground on the load circuit or a shorted component.
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
14 |
Important: : If the fuse is open, locate and repair a short to ground on the load circuit or a shorted component.
Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
15 | Replace the Fan #3 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
16 | Repair
the open in the Engine Coolant Fan Motor 2 feed circuit between the Fan #3
Relay and the splice. Refer to
Connector Repairs
,
Testing for Intermittent Conditions and Poor Connections
, and
Wiring Repairs
in Wiring Systems. The open/poor connection may be in the
Did you complete the repair? | -- | Go to Evaporative Emission Control System Diagnosis Electric Cooling Fan Functional Check | -- |
17 | Repair
the High Speed Fans Control circuit for an open or a short to battery positive
voltage. Refer to
Connector Repairs
,
Testing for Intermittent Conditions and Poor Connections
,
and
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 High Speed Fans Control circuit between the Fan Cont #2 Relay
and the splice. Refer to
Connector Repairs
,
Testing for Intermittent Conditions and Poor Connections
, and
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 | -- |
19 | Repair
the open in the ground circuit. Refer to
Connector Repairs
,
Testing for Intermittent Conditions and Poor Connections
, and
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 | -- |
20 | Replace the Fan Cont #2 Relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Functional Check | -- |
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 Cont #2 Relay coil feed circuit. Refer to
Connector Repairs
,
Testing for Intermittent Conditions and Poor Connections
, and
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 | -- |
22 | Inspect the PCM connections. Refer to Connector Repairs , Testing for Intermittent Conditions and Poor Connections , and Wiring Repairs in Wiring Systems. 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 | -- |
