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.

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 both cooling fans operating at low speed?

Go to Step 4

Go to Step 3

3

Is the left cooling fan operating at high speed?

Go to Step 5

Go to Testing for Intermittent Conditions and Poor Connections

4

Remove the low speed fan relay.

Did the fans turn OFF?

Go to Step 8

Go to Step 6

5

Remove the high speed fan relay.

Did the left cooling fan turn OFF?

Go to Step 9

Go to Step 7

6

Repair the cooling fan motor supply voltage circuit of the right cooling fan for a short to voltage. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 12

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7

Repair the cooling fan motor supply voltage circuit of the left cooling fan for a short to voltage. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 12

--

8

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

Did you find and correct the condition?

Go to Step 12

Go to Step 10

9

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

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

Replace the low speed fan relay.

Did you complete the replacement?

Go to Step 12

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11

Replace the high speed fan relay.

Did you complete the replacement?

Go to Step 12

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12

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2