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For 1990-2009 cars only

Cooling Fan Inoperative Low Speed

Table 1: Reference Table

Reference Table

Symptom

Causes

Fan motors inoperative in high speed only

    • Open in the fan 2 relay coil supply voltage circuit.
    • Open in the fan 2 relay coil control circuit.
    • Open in the fan motor high speed ground circuit between the fan motors and the fan 2 relay.
    • Open in the fan motor high speed ground circuit between the fan 2 relay and S240.
    • Malfunctioning fan 2 relay.
    • Malfunctioning fan motor.

Fan motors inoperative in low speed only

    • Open in the fan 1 relay coil supply voltage circuit.
    • Open in the fan 1 relay coil control circuit.
    • Open in the fan motor low speed ground circuit between the fan motors and the fan 1 relay.
    • Open in the fan motor low speed ground circuit between the fan 1 relay and S240.
    • Malfunctioning fan 1 relay.
    • Malfunctioning fan motor.

One fan motor only inoperative

    • Open in the fan motor supply voltage circuit.
    • Open in the fan motor low speed ground circuit.
    • Open in the fan motor high speed ground circuit.
    • Malfunctioning fan motor.

Both fan motors inoperative

    • Open or high resistance between the Engine Controls Telematics fuse and S105.
    • Open or high resistance between S240 and G103.

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

DEFINITION: The cooling fan motors are inoperative in low speed.

1

Did you review the Cooling System Description and Operation and perform the necessary inspections?

Go to Step  2

Go to Symptoms - Engine Cooling

2

  1. Connect a scan tool.
  2. Use the scan tool to command the low speed fan ON.

Do the cooling fans operate at low speed?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Disconnect the low speed fan motor.
  2. Connect a test lamp from the fan motor supply voltage circuit to the fan motor low speed ground circuit.
  3. Use the scan tool to command the low speed fan ON.

Does the test lamp illuminate?

Go to Step  10

Go to Step  4

4

  1. Remove the fan 1 relay.
  2. Install a 30-amp fused jumper between the low speed fan motor ground circuit and the fan 1 relay ground circuit, between cavities 30 and 87, of the cooling fan 1 relay connector.

Do the cooling fans operate at low speed?

Go to Step 5

Go to Step  7

5

Test the fan 1 relay coil supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 6

6

Test the fan 1 relay coil control circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test the fan motor low speed ground circuit for an open between the fan motors and the fan 1 relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 8

8

Repair the open in the fan motor low speed ground circuit between the fan 1 relay and S240. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

--

9

Inspect for a poor connection at the harness connector of the fan 1 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

10

Inspect for a poor connection at the harness connector of the fan motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 12

11

Replace the fan 1 relay. Refer to Cooling Fan Relay Replacement .

Did you complete the replacement?

Go to Step 13

--

12

Replace the fan motor. Refer to Engine Cooling Fan Replacement .

Did you complete the replacement?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2

Cooling Fan Inoperative High Speed

Table 1: Reference Table

Reference Table

Symptom

Causes

Fan motors inoperative in high speed only

    • Open in the fan 2 relay coil supply voltage circuit.
    • Open in the fan 2 relay coil control circuit.
    • Open in the fan motor high speed ground circuit between the fan motors and the fan 2 relay.
    • Open in the fan motor high speed ground circuit between the fan 2 relay and S240.
    • Malfunctioning fan 2 relay.
    • Malfunctioning fan motor.

Fan motors inoperative in low speed only

    • Open in the fan 1 relay coil supply voltage circuit.
    • Open in the fan 1 relay coil control circuit.
    • Open in the fan motor low speed ground circuit between the fan motors and the fan 1 relay.
    • Open in the fan motor low speed ground circuit between the fan 1 relay and S240.
    • Malfunctioning fan 1 relay.
    • Malfunctioning fan motor.

One fan motor only inoperative

    • Open in the fan motor supply voltage circuit.
    • Open in the fan motor low speed ground circuit.
    • Open in the fan motor high speed ground circuit.
    • Malfunctioning fan motor.

Both fan motors inoperative

    • Open or high resistance between the Engine Controls Telematics fuse and S105.
    • Open or high resistance between S240 and G103.

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

DEFINITION: The cooling fan motors are inoperative in high speed.

1

Did you review the Cooling System Description and Operation and perform the necessary inspections?

Go to Step  2

Go to Symptoms - Engine Cooling

2

  1. Connect a scan tool.
  2. Use the scan tool to command the high speed fan ON.

Do the cooling fans operate at high speed?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Disconnect the high speed fan motor.
  2. Connect a test lamp from the fan motor supply voltage circuit to the fan motor high speed ground circuit.
  3. Use the scan tool to command the high speed fan ON.

Does the test lamp illuminate?

Go to Step  10

Go to Step  4

4

  1. Remove the fan 2 relay.
  2. Install a 30-amp fused jumper between the high speed fan motor ground circuit and the fan 2 relay ground circuit, between cavities 30 and 87, of the cooling fan 2 relay connector.

Do the cooling fans operate at high speed?

Go to Step 5

Go to Step  7

5

Test the fan 2 relay coil supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 6

6

Test the fan 2 relay coil control circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test the fan motor high speed ground circuit for an open between the fan motors and the fan 2 relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 8

8

Repair the open in the fan motor high speed ground circuit between the fan 2 relay and S240. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

--

9

Inspect for a poor connection at the harness connector of the fan 2 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

10

Inspect for a poor connection at the harness connector of the fan motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 12

11

Replace the fan 2 relay. Refer to Cooling Fan Relay Replacement .

Did you complete the replacement?

Go to Step 13

--

12

Replace the fan motor. Refer to Engine Cooling Fan Replacement .

Did you complete the replacement?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2

Cooling Fan Inoperative One Fan Only

Table 1: Reference Table

Reference Table

Symptom

Causes

Fan motors inoperative in high speed only

    • Open in the fan 2 relay coil supply voltage circuit.
    • Open in the fan 2 relay coil control circuit.
    • Open in the fan motor high speed ground circuit between the fan motors and the fan 2 relay.
    • Open in the fan motor high speed ground circuit between the fan 2 relay and S240.
    • Malfunctioning fan 2 relay.
    • Malfunctioning fan motor.

Fan motors inoperative in low speed only

    • Open in the fan 1 relay coil supply voltage circuit.
    • Open in the fan 1 relay coil control circuit.
    • Open in the fan motor low speed ground circuit between the fan motors and the fan 1 relay.
    • Open in the fan motor low speed ground circuit between the fan 1 relay and S240.
    • Malfunctioning fan 1 relay.
    • Malfunctioning fan motor.

One fan motor only inoperative

    • Open in the fan motor supply voltage circuit.
    • Open in the fan motor low speed ground circuit.
    • Open in the fan motor high speed ground circuit.
    • Malfunctioning fan motor.

Both fan motors inoperative

    • Open or high resistance between the Engine Controls Telematics fuse and S105.
    • Open or high resistance between S240 and G103.

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

DEFINITION: One cooling fan motor is inoperative.

1

Did you review the Cooling System Description and Operation and perform the necessary inspections?

Go to Step  2

Go to Symptoms - Engine Cooling

2

  1. Connect a scan tool.
  2. Use the scan tool to command the affected fan ON.

Does the cooling fan operate?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Disconnect the affected fan motor.
  2. Connect a test lamp from the fan motor supply voltage circuit to the fan motor low speed ground circuit.
  3. Connect a test lamp from the fan motor supply voltage circuit to the fan motor high speed ground circuit.
  4. Use the scan tool to command the affected fan ON in each speed.

Does the test lamp illuminate in each speed?

Go to Step  7

Go to Step  4

4

Test the fan motor low speed ground circuit for an open between the fan motor and S156. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 5

5

Test the fan motor high speed ground circuit for an open between the fan motor and S157. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 6

6

Repair the open in the fan motor supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

--

7

Inspect for a poor connection at the harness connector of the fan motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

8

Replace the fan motor. Refer to Engine Cooling Fan Replacement .

Did you complete the replacement?

Go to Step 9

--

9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2