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 in Vehicle DTC Information

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 in Wiring Systems

3

Are both cooling fans running continuously?

Go to Step 5

Go to Step 4

4

Remove the FAN CONT #2 relay.

Did the right cooling fan turn OFF?

Go to Step 8

Go to Step 6

5

Remove the FAN CONT #1 relay.

Did the cooling fans turn OFF?

Go to Step 10

Go to Step 7

6

Remove the FAN CONT #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 in Wiring Systems.

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 in Wiring Systems.

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 in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

10

Inspect for poor connections at the FAN CONT #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 14

Go to Step 12

11

Inspect for poor connections at the FAN CONT #3 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 14

Go to Step 13

12

Replace the FAN CONT #1 relay.

Did you complete the replacement?

Go to Step 14

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13

Replace the FAN CONT #3 relay.

Did you complete the replacement?

Go to Step 14

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14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2