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 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 cooling fan mode relay.

Did the right cooling fan turn OFF?

Go to Step 8

Go to Step 9

5

Inspect for a short to voltage in the left cooling fan supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 6

6

Inspect for a short to ground in the low speed cooling fan relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

7

Replace the cooling fan 1 relay.

Did you complete the replacement?

Go to Step 10

--

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 10

--

9

Remove the cooling fan 2 relay.

Did the cooling fan turn OFF?

Go to Step 10

Go to Step 11

10

Replace the cooling fan 2 relay.

Did you complete the replacement?

Go to Step 12

--

11

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

Did you complete the repair?

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