Schematic Reference: Refer to Engine Cooling Schematics .

DEFINITION: Cooling fan motors are inoperative at either high, low, or both speeds.

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Refer to Diagnostic System Check - Vehicle

1. Install the scan tool.
2. Ignition ON, engine OFF.
3. With a scan tool, command the fans low speed ON and OFF.

Do the low speed engine cooling fans turn ON and OFF with each command?

Go to Step 3

Go to Step 4

Note: A few seconds delay occurs before the engine control module (ECM) changes the cooling fan speed. With a scan tool, command the fans high speed ON and OFF.

Do the high speed engine cooling fans turn ON and OFF with each command?

Refer to Symptoms - Engine Cooling

Go to Step 6

Note: 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 fused jumper wire, repair the cooling fan motor supply voltage circuit of the right cooling fan motor for a short circuit to ground.

1. Disconnect the low speed fan 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 at low speed?

Go to Step 14

Go to Step 5

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

Does the test lamp illuminate?

Go to Step 9

Go to Step 8

Does the cooling fan operate at high speed?

Go to Step 15

Go to Step 7

Inspect the ground circuit of the Low Speed fan relay for an open circuit or high resistance.

Did you find and correct the condition?

System OK

Go to Step 15

1. Install the low speed fan 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 12

Step 13

1. Install the low speed fan relay.
2. Disconnect the cooling fan motor 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 11

Go to Step 10

Inspect the cooling fan motor supply voltage circuit for an open circuit or high resistance.

Did you find and correct the condition?

System OK

Go to Step 15

Inspect the ground circuit of the cooling fan for an open circuit or high resistance.

Did you find and correct the condition?

System OK

Go to Step 16

Inspect the cooling fan low reference circuit for an open circuit or high resistance.

Did you find and correct the condition?

System OK

Go to Step 16

Inspect the cooling fan motor supply voltage circuit of the cooling fan for an open circuit or high resistance.

Did you find and correct the condition?

System OK

Inspect the battery positive voltage circuit for an open circuit or high resistance.

Inspect for poor connections at the low speed fan relay. Refer to Symptoms - Engine Cooling .

Did you find and correct the condition?

System OK

Replace the low speed fan relay.

Inspect for poor connections at the high speed fan relay. Refer to Symptoms - Engine Cooling .

Did you find and correct the condition?

System OK

Replace the high speed fan relay.

Inspect for poor connections at the harness connector of the cooling fan. Refer to Symptoms - Engine Cooling

Did you find and correct the condition?

System OK

Replace the cooling fan.