GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

DEFINITION: One or both engine cooling fan motors run continuously in high or low speed modes.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Turn ON the ignition, with the engine OFF.

Are one or both cooling fans ON?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

Are both cooling fans running continuously?

Go to Step 5

Go to Step 4

4

Remove the fan 2 relay.

Did the right cooling fan turn OFF?

Go to Step 8

Go to Step 6

5

Remove the fan 1 relay.

Did the cooling fans turn OFF?

Go to Step 10

Go to Step 7

6

Remove the fan 3 relay.

Did the right cooling fan turn OFF?

Go to Step 11

Go to Step 9

7

Repair the short to voltage in the left cooling fan motor supply voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 14

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8

Repair the short to voltage in the left cooling fan low reference circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 14

--

9

Repair the short to voltage in the right cooling fan motor supply voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 14

--

10

Inspect for poor connections at the fan 1 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 12

11

Inspect for poor connections at the fan 3 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 13

12

Replace the fan 1 relay.

Did you complete the replacement?

Go to Step 14

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13

Replace the fan 3 relay.

Did you complete the replacement?

Go to Step 14

--

14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2