GM Service Manual Online
For 1990-2009 cars only
Table 1: Reference Table

Reference Table

Symptom

Causes

Both fan motors always ON.

    • Short to ground in the fan 1 relay coil control circuit
    • Short to ground in the fan motor low speed ground circuit
    • Fan relay 1 internal contacts shorted together

One fan motor always ON.

    • Short to ground in the fan 2 relay coil control circuit
    • Short to ground in the fan motor ground circuit
    • Fan relay 2 internal contacts shorted together

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

DEFINITION: The cooling fan motors are always on in low speed.

1

Did you review the Cooling System Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Engine Cooling

2

With the engine OFF.

Is one or both the fan motors running continuously?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections .

3

Are both fan motors ON?

Go to Step 7

Go to Step 4

4

Remove the fan 2 relay from the underhood fuse block.

Is the fan motor running continuously?

Go to Step 6

Go to Step 5

5

Test the fan 2 relay coil control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 11

6

Repair the short to ground in the fan motor ground circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

--

7

Remove the fan 1 relay from the underhood fuse block.

Are the fan motors running continuously?

Go to Step 8

Go to Step 9

8

Repair the short to ground in the fan motor ground circuit between the fan motors and the fan 1 relay. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

--

9

Test the fan 1 relay coil control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 12

Go to Step 10

10

Replace the fan 1 relay. Refer to Cooling Fan Relay Replacement .

Did you complete the replacement?

Go to Step 12

--

11

Replace the fan 2 relay. Refer to Cooling Fan Relay Replacement .

Did you complete the replacement?

Go to Step 12

--

12

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2