Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

DEFINITION: The cooling fan motor is inoperative in either high or low speeds.

Did you perform the Diagnostic System Check - Engine Cooling?

Go to Step 2

Go to Diagnostic System Check - Engine Cooling

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the Fan Control 1 ON and OFF.

Does the cooling fan turn ON and OFF in low speed with each command?

Go to Step 3

Go to Step 4

Important: A 3 second delay occurs before the engine control module (ECM) changes the cooling fan speed.

With a scan tool, command the Fan Control 2 Speed ON and OFF.

Does the cooling fan turn ON and OFF in high speed with each command?

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

Go to Step 6

Important: Do NOT remove the jumper wire that you will be connecting until your testing is completed. If the low speed fan fuse opens when you connect the jumper wire, repair the cooling fan motor supply voltage circuit of the cooling fan motor for a short to ground.

1. Disconnect the cool fan low relay.
2. Connect a jumper wire between the battery positive voltage circuit and the cooling fan motor supply voltage circuit of the low speed fan relay.

Does the cooling fan operate in low speed?

Go to Step 11

Go to Step 5

1. Disconnect the cool fan high relay.
2. With a test lamp connected to a good ground, probe the cooling fan low reference circuit at the cooling fan resistor.

Does the test lamp illuminate?

Go to Step 9

Go to Step 8

Does the cooling fan operate at high speed?

Go to Step 12

Go to Step 7

Inspect the ground circuit of the cool fan high relay for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 12

1. Install the cool fan high relay.
2. Disconnect the cooling fan electrical connector.
3. With a test lamp connected to a good ground, probe the cooling fan motor supply voltage circuit at the cooling fan motor connector.

Does the test lamp illuminate?

Go to Step 10

Go to Step 9

Inspect the cooling fan motor supply voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 14

Inspect the ground circuit of the cooling fan for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 13

Inspect for poor connections at the cool fan low 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 18

Go to Step 15

Inspect for poor connections at the cool fan high 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 18

Go to Step 13

Inspect for poor connections at the harness connector of the cooling fan. 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 18

Go to Step 17

Inspect the battery positive voltage circuit for an open or high resistance. Refer to Wiring Repairs and Circuit Testing in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 16

Replace the cool fan low relay.

Did you complete the replacement?

Go to Step 18

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Replace the cool fan high relay.

Did you complete the replacement?

Go to Step 18

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

Did you complete the replacement?

Go to Step 18

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3