For 1990-2009 cars

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

Engine Controls Components
Powertrain Control Module Description
HO2S 1 and HO2S 2
OBD II Symbol Description Notice
Ground Distribution Schematics
Ground Distribution Schematics
Power Distribution Schematics
Ground Distribution Schematics
.

### 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

(1) | G103
(2) | C102

.

### 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:

1. The PCM will enable the engine cooling fans when certain DTCs are set. Refer to applicable DTC table first before proceeding with this table.

2. Allow ECT to cool below 100°C (212°F) before proceeding with diagnosis.

#### Electric Cooling Fan Functional Check

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Are any DTCs set? | -- | Go to applicable DTCs | Go to Step 3
3 |

1. Install a scan tool.
2. Engine coolant temperature must be below the specified value for all the fan diagnoses.
3. Turn ON the ignition, with the engine and A/C OFF.

Are the cooling fans OFF?

100°C (212°F)

Go to Step 4

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 Step 5 | 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 Step 6 | Go to Electric Cooling Fan Diagnosis Electric Cooling Fan Table #3
6 |

1. Exit outputs screen on the scan tool.
2. Idle the engine leaving the A/C OFF.

Are the cooling fans ON?

--

Go to Step 8

Go to Step 7

7 | Turn ON the A/C. Are the cooling fans ON? | -- | System OK | Go to Step 9
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 | Go to Step 10
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 | --

#### Electric Cooling Fan Table #1

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Step 2 | Go to Electric Cooling Fan Diagnosis Functional Check
2 | Disconnect #1 fan control relay. Are both fans OFF? | -- | Go to Step 8 | Go to Step 3
3 | Disconnect mode control relay. Are both fans OFF? | -- | Go to Step 4 | Go to Step 10
4 |

1. Disconnect the left fan.
2. Probe terminal B of the left fan connector using a test lamp that is connected to ground.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 5

5 | Probe terminal A of the left fan connector using a test lamp that is connected to ground. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 6
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? | -- | Go to Step 7 | Go to Step 13
7 |

1. Turn OFF the ignition.
2. Leave the test lamp installed.
3. Disconnect the PCM.
4. Turn ON the ignition, with the engine OFF.

Is the test lamp still illuminated?

--

Go to Step 14

Go to Step 16

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? | -- | Go to Step 9 | Go to Step 13
9 |

1. Turn OFF the ignition.
2. Leave the test lamp installed.
3. Disconnect the PCM.
4. Turn ON the ignition, with the engine OFF.

Is the test lamp still illuminated?

--

Go to Step 14

Go to Step 16

10 |

1. Inspect the following components for a short to voltage:

• | The right fan feed circuit (532)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you find and correct the condition?

--

Go to Electric Cooling Fan Diagnosis Functional Check

Go to Step 15

11 |

1. Inspect the following components for a short to voltage:

• | The left fan feed circuit (409)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

12 |

1. Inspect the following components for a short to voltage:

• | The #2 fan control relay switch feed circuit (532)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

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 |

1. Inspect the following components for a short to ground:

• | The right fan control circuit (473)--Refer to Wiring Repairs in Wiring Systems.

• | The left fan control circuit (335)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

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 | --

#### Electric Cooling Fan Table #2

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Step 2 | Go to Electric Cooling Fan Diagnosis Functional Check
2 | Did either fan turn ON when the Low Speed Fans were commanded ON? | -- | Go to Step 3 | Go to Step 4
3 |

1. Disconnect the mode control relay.
2. Turn ON the ignition.

Did the left fan turn OFF?

--

Go to Step 17

Go to Step 20

4 |

1. Disconnect the #1 fan control relay.
2. Probe the left fan control circuit (335) at the #1 fan control relay connector terminal (85) using a J 35616-200 test lamp that is connected to battery positive voltage.
3. With a scan tool, command the Low Speed Fans ON.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 12

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? | -- | Go to Step 6 | Go to Step 16
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? | -- | Go to Step 22 | Go to Step 7
7 |

1. Disconnect the left fan.
2. Probe the left fan harness connector terminal B with a test lamp that is connected to ground.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 23

8 | Connect a second fused jumper wire between the left fan harness connector terminals. Is the right fan ON? | -- | Go to Step 15 | Go to Step 9
9 |

1. Reconnect the left fan.
2. Disconnect the mode control relay.
3. Probe the switch feed circuit (504) at the mode control relay connector terminal (30) using a test lamp that is connected to ground.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 24

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? | -- | Go to Step 26 | Go to Step 11
11 |

1. Reconnect mode control relay.
2. Disconnect the right fan.
3. Probe fan harness connector terminal B with a test lamp that is connected to ground.

Did the test lamp illuminate?

--

Go to Step 15

Go to Step 17

12 |

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Probe the left fan control circuit at the PCM connector, with a fused jumper wire that is connected to ground.

Does the test lamp illuminate?

--

Go to Step 14

Go to Step 25

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 | Go to Step 27
14 |

1. Inspect the following components for a short to battery positive voltage:

• | The left fan control circuit (335)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

15 |

1. Inspect the following components for a open:

• | The fan motor ground circuit--Refer to Wiring Repairs in Wiring Systems.

• | The fan motor connections-- Refer to Testing for Intermittent Conditions and Poor Connections , and Connector Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

• | Ground splice pack--Refer to Engine Controls Component Views

#### Left Side of Engine

(1) | G103
(2) | C102

.

2. Repair as needed.

Did you find and correct the condition?

--

Go to Electric Cooling Fan Diagnosis Functional Check

Go to Step 21

16 |

1. Inspect for an open or short to ground in the circuit that did not illuminate the test lamp
2. Replace the fuse if necessary.
3. If this does not correct the problem, replace the underhood junction block. Refer to Engine Controls Component Views

   #### Underhood Junction Block

   .

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

17 |

1. Inspect the following components for an open or short to ground:

• | The right fan feed circuit (532)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Replace Cool Fan #2 Fuse if necessary. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

Go to Step 26

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 |

1. Inspect the following components for a short to ground:

• | The mode control relay switch feed circuit (504)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you find and correct the condition?

--

Go to Electric Cooling Fan Diagnosis Functional Check

Go to Step 26

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 |

1. Inspect the following components for an open:

• | The left fan feed circuit (409)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

24 |

1. Inspect the following components for an open:

• | The mode control relay switch feed circuit (504)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

25 |

1. Inspect the following components for an open:

• | The left fan control circuit--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

--

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 | --

#### Electric Cooling Fan Table #3

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Electric Cooling Fan Functional Check? | -- | Go to Step 2 | Go to Electric Cooling Fan Diagnosis Functional Check
2 |

1. With a scan tool, command the Low Speed Fans ON.
2. Command the High Speed Fans ON while observing the fans.

Did both fans operate with no change?

--

Go to Step 8

Go to Step 3

3 | Did the left fan stop operating? | -- | Go to Step 9 | Go to Step 4
4 |

1. Disconnect the #2 fan control relay.
2. Probe the right fan control circuit (473) at the #2 fan control relay connector terminal (85) using a test lamp that is connected to battery positive voltage.
3. Using a scan tool, command the High Speed Fans ON .

Does the test lamp illuminate after several seconds?

--

Go to Step 5

Go to Step 12

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? | -- | Go to Step 6 | Go to Step 13
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? | -- | Go to Step 7 | Go to Step 14
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? | -- | Go to Step 15 | Go to Step 16
8 |

1. Turn OFF the ignition.
2. Disconnect the PCM.
3. Disconnect the #1 fan control relay.
4. Jumper the switch feed circuit (742) and the left fan feed circuit (409) together at the #1 fan control relay connector terminals 30 and 87.
5. Turn ON the ignition.
6. Probe the right fan control circuit (473) at the PCM harness connector with a test lamp that is connected to ground.

Do the fans switch from low to high speed?

--

Go to Step 22

Go to Step 17

9 |

1. Disconnect mode control relay.
2. Probe the right fan control circuit (473) at the mode control relay connector terminal (86) using a test lamp that is connected to battery positive voltage.
3. Using a scan tool, command the High Speed Fans ON.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 18

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? | -- | Go to Step 11 | Go to Step 19
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? | -- | Go to Step 20 | Go to Step 21
12 |

1. Inspect the following components for an open between fan #2 fan control relay and the splice:

• | The right fan control circuit (473)--Refer to Wiring Repairs in Wiring Systems.

• | Ground splice pack--Refer to Engine Controls Component Views

#### Left Side of Engine

(1) | G103
(2) | C102

.

2. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

13 |

1. Inspect the following components for an open :

• | The #2 fan control relay coil feed circuit--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you complete the replacement?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

14 |

1. Inspect the following components for an open or short to ground:

• | The #2 fan control relay switch feed circuit (2340)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

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 |

1. Inspect the following components for an open:

• | The right fan feed circuit (532) between #2 fan control relay and the splice--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

17 |

1. Inspect the following components for an open or short to battery positive voltage:

• | The right fan control circuit (473)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

18 |

1. Inspect the following components for an open:

• | The right fan control circuit (473) between mode control relay and the splice--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

Did you complete the repair?

--

Go to Electric Cooling Fan Diagnosis Functional Check

--

19 |

1. Inspect the following components for an open:

• | Ground circuit (450)--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

• | Ground splice back--Refer to Engine Controls Component Views

#### Left Side of Engine

(1) | G103
(2) | C102

2. Repair as needed.

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 |

1. Inspect the following components for an open:

• | The mode control relay coil feed circuit--Refer to Wiring Repairs in Wiring Systems.

• | Underhood junction block--Refer to Engine Controls Component Views

#### Underhood Junction Block

.

2. Repair as needed.

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 | Go to Step 23
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 | --