GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1999 🢒 Catera 🢒 Engine 🢒 Engine Cooling 🢒 Cooling Fan System Check

Step

Action

Yes

No

1

Turn the ignition key to the ON position.

Does the heater water auxiliary pump operate?

Go to Step 2

Go to Step 3

2

Make sure the engine temperature is below 95°C  ( 203°F ).

Are the auxiliary cooling fans and/or the electric cooling fan inoperative with the engine temperature below 95°C (203°F)?

Go to Step 4

Go to Step 5

3

The heater water auxiliary pump does not operate. Refer to Auxiliary Water Pump Inoperative

Does the Heater water auxiliary pump operate properly?

Go to Step 27

--

4
  1. Connect a fused jumper between pin 1 of the coolant fan test connector and a known good ground.
  2. Grounding pin 1 of the coolant fan test connector will simulate the closing of the primary cooling fan temperature switch stage 1 contacts, this will energize the fan control relay K26.

Does the auxiliary engine coolant fan #1 and auxiliary coolant fan #2 operate at low speed?

Go to Step 6

Go to Step 7

5

The auxiliary cooling fans run with the engine temperature below 95°C (203°F) Refer to Cooling Fan Always On - Auxiliary

Are the engine cooling fans operating properly?

Go to Step 27

--

6

Check that the electric cooling fan is operating at low speed.

Is the electric cooling fan is operating at low speed?

Go to Step 9

Go to Step 8

7

The auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 do not operate. Refer to Cooling Fan Inoperative - Auxiliary

Are the engine cooling fans operating properly?

Go to Step 27

--

8

The electric cooling fan does not operate at low speed. Refer to Cooling Fan Inoperative at Low Speed - Electric

Are the engine cooling fans operating properly?

Go to Step 27

--

9

Check if the water auxiliary pump is operating.

Does the water auxiliary pump operate?

Go to Step 10

Go to Step 11

10
  1. Leave all previously connected jumpers connected.
  2. Connect a fused jumper between pin 5 of the coolant fan test connector and a known good ground.
  3. Grounding pin 5 of the coolant fan test connector will simulate the closing of the secondary cooling fan temperature switch, this will energize the fan control relay K28 and fan control relay K52.

Does the auxiliary engine coolant fan #1 operate at high speed?

Go to Step 12

Go to Step 13

11

Water auxiliary pump does not operate. Refer to Auxiliary Water Pump Inoperative

Does the water auxiliary pump operate properly?

Go to Step 27

--

12

Check if the auxiliary engine coolant fan #2 is operating at high speed.

Does the auxiliary engine coolant fan #2 operate at high speed? operate at high speed?

Go to Step 14

Go to Step 15

13

The auxiliary engine coolant fan #1 does not operate at high speed. Refer to Cooling Fan Inoperative - Auxiliary

Are the engine cooling fans operating properly?

Go to Step 27

--

14
  1. Leave all previously connected jumpers connected.
  2. Connect a fused jumper between pin 4 of the coolant fan test connector and a known good ground.
  3. Grounding pin 4 of the coolant fan test connector will simulate the closing of the primary cooling fan temperature switch stage 2 contacts, this will energize the fan control relay K67.

Does the electric cooling fan operate at high speed?

Go to Step 16

Go to Step 17

15

The auxiliary engine coolant fan #2 does not operate at high speed. Refer to Cooling Fan Inoperative - Auxiliary

Are the engine cooling fans operating properly?

Go to Step 27

--

16
  1. Remove all previously connected jumpers.
  2. Start the engine and allow it to run.
  3. Turn the A/C compressor clutch coil ON.

Does the auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 run at low speed when the compressor clutch coil is turned ON?

Go to Step 19

Go to Step 18

17

The electrical cooling fan does not operate at high speed. Refer to Cooling Fan Inoperative

Are the engine cooling fans operating properly?

Go to Step 27

--

18

The auxiliary engine coolant fan #1 and auxiliary engine cooling fan #2 do not operate when the compressor is turned ON. Refer to Cooling Fan Inoperative - Auxiliary

Are the engine cooling fans operating properly?

Go to Step 27

--

19
  1. Install the scan tool.
  2. Monitor the engine temperature using the scan tool.
  3. Remove any previously connected jumpers.
  4. Turn the A/C compressor clutch coil OFF.
  5. Allow the engine to run until the primary cooling fan temperature switch reaches 100°C (212°F). The stage 1 contacts should close and energize the fan control relay K26.

Does the auxiliary engine coolant fan #1 and auxiliary coolant fan #2 operate at low speed?

Go to Step 20

Go to Step 21

20

Continue to allow the engine to run until the secondary cooling fan temperature switch reaches 105°C (221°F). The secondary cooling fan temperature switch should close and energize the fan control relay K28 and fan control relay K52.

Does the auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 operate at high speed?

Go to Step 22

Go to Step 23

21
  1. Locate an open or a high resistance in circuit XP30.
  2. Repair the open or the high resistance in circuit XP30.
  3. Replace the primary cooling fan temperature switch if these circuits are OK. Refer to Engine Cooling Fan Control Switch Replacement

Are the engine cooling fans operating properly?

Go to Step 27

--

22

Continue to allow the engine to run until the primary cooling fan temperature switch reaches 110°C (230°F). The stage 2 contacts should close and energize the fan control relay K67.

Does the electric cooling fan operate at high speed?

Go to Step 25

Go to Step 24

23
  1. Locate an open or a high resistance in circuit XM122.
  2. Repair the open or the high resistance in circuit XM122.
  3. Replace the secondary cooling fan temperature switch if these circuits are OK. Refer to Engine Cooling Fan Control Switch Replacement

Are the engine cooling fans operating properly?

Go to Step 27

--

24
  1. Locate an open or a high resistance in circuit XM5.
  2. Repair the open or the high resistance in circuit XM5.
  3. Replace the primary cooling fan temperature switch if these circuits are OK. Refer to Engine Cooling Fan Control Switch Replacement .

Are the engine cooling fans operating properly?

Go to Step 27

--

25
  1. Turn the A/C compressor clutch coil on.
  2. Continue to operate the engine until the A/C refrigerant pressure switch reaches 275 psi.

Does the auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 operate at high speed?

Go to Step 27

Go to Step 26

26

The auxiliary engine coolant fan #1 and fan #2 do not operate at high speed when the A/C refrigerant pressure switch reaches 275 psi. Refer to Cooling Fan Inoperative - Auxiliary .

Are the engine cooling fans operating properly?

Go to Step 27

--

27

Confirm that the engine cooling fans and auxiliary water pumps operate properly . Refer to Cooling System Description .

Do the engine cooling fans and auxiliary water pumps operate properly

System OK

Go to Step 1