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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Cavalier 🢒 Engine 🢒 Engine Controls - 2.2L 🢒 Electric Cooling Fan Diagnosis

Object Number: 50811 Size: MF
Engine Controls Components
Powertrain Control Module Connector End Views
Cooling Fan Controls
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Diagnosis

For specific system description, components and wiring, refer to Electrical Diagnosis.

Circuit Description

The electric cooling fan is controlled by the Powertrain Control Module (PCM) through the fan relay based on inputs from the engine coolant temperature (ECT) sensor and intake air temperature (IAT) sensors, the A/C selector switch, A/C refrigerant pressure sensor and the vehicle speed sensor (VSS). The PCM controls the cooling fan by grounding the cooling fan control circuit which turns ON the cooling fan relay.

The fan relay will be commanded ON when the following conditions are met:

    • Engine coolant temperature reaches 106°C (223°F) or more.
    • A/C clutch requested.
    • Vehicle speed is less than 38 MPH.
        The cooling fan relay will be commanded ON regardless of vehicle speed when:
       - Any DTC is set that causes the malfunction indictor lamp (MIL) to be illuminated.
       - Engine coolant temperature is 151°C (304°F) or more.
       - A/C refrigerant pressure is high.

The cooling fan may be commanded ON when the engine is not running under fan run-on conditions described previously in this section.

Diagnostic Aids
    • If the owner complained of an overheating problem, it must be determined if the complaint was due to an actual boil over, or if the Temp light, or temperature gage indicated overheating.
    • Check for the proper amount of coolant in the system.
    • If the gage, or light, indicates overheating, but no boil over is detected, the gage or light circuit should be checked. The gage accuracy can also be checked by comparing the engine coolant temperature sensor reading using a scan tool with the gage reading.
    • If the engine is actually overheating, and the gage indicates overheating, but the cooling fan is not coming ON, the Engine Coolant Temperature (ECT) sensor may have shifted out of calibration and should be replaced. Refer to Temperature vs Resistance for a Temperature vs. Resistance table.
    • If the engine is overheating, and the cooling fan is ON, the cooling system should be checked. Refer to Engine Cooling .

Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

  1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.

    2.

  2. Cooling system operation and level should be checked before determining if any electrical conditions are present causing a cooling system failure.

    3.

  3. With the engine OFF, the cooling fan should not be commanded ON by the PCM.

    4.

  4. If the cooling fan turns OFF after disconnecting the PCM connectors, the PCM was causing the fan to be ON constantly.

    5.

  5. A test light that illuminates indicates that the cooling fan battery feed circuit (CKT 409) is shorted to battery voltage. The cooling fan will also remain engaged when the cooling fan relay electrical connector is disconnected.

    6.

  6. Connecting CKTs 542 and 409 together bypasses the PCMs control of the cooling fan. A cooling fan that fails to engage at this point indicates that the malfunction is in CKT 409, the cooling fan or cooling fan ground circuit.

    7.

  7. Both battery feed circuits are supplied to the cooling fan relay through the same fuse. No voltage on both circuits would indicate that the fuse is open. Locate and repair any shorts that may have caused the fuse to open before replacement.

    8.

  8. With the engine stopped and the cooling fan relay commanded ON, the PCM should ground the A/C relay circuit. This will also illuminate the test light.

    9.

  9. This step determines if the reason the cooling fan did not come ON was due to an open battery feed circuit to the cooling fan.

    10.

  10. Reprogram the replacement PCM. Perform the crankshaft position system variation procedure. Refer to PCM Replacement/Programming for PCM reprogramming and CKP System Variation Learn Procedure for the crankshaft position system variation procedure.

    11.

  11. If no malfunctions have been found at this point, refer to Diagnostic Aids for additional checks and information.

Cooling Fan

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check for 2.4L, or Powertrain On Board Diagnostic (OBD) System Check for 2.2L

2
  1. Turn ON the ignition switch leaving the engine OFF.
  2. Install a scan tool.
  3. Check for any DTCs with the scan tool.

Were any DTCs present?

--

Go to DTC tables first

Go to Step 3

3

  1. Turn OFF the ignition switch.
  2. Check the water pump belt condition and tension.
  3. Check the cooling system level.

Were any repairs necessary?

--

Go to Step 27

Go to Step 4

4

  1. Turn ON the ignition switch leaving the engine OFF.
  2. Allow the engine coolant temperature to cool below the specified value.

Is the cooling fan OFF?

98°C (209°F)

Go to Step 5

Go to Step 6

5

Command ON the cooling fan relay with the scan tool.

Is the cooling fan ON?

--

Go to Step 27

Go to Step 7

6

  1. Turn OFF the ignition switch.
  2. Disconnect the PCM electrical connectors at the PCM.

Is the cooling fan OFF?

--

Go to Step 26

Go to Step 8

7
  1. Remove the cooling fan relay. Refer to A/C Compressor and Cooling Fan Relays Replacement .
  2. Connect a test light to ground.
  3. Probe the battery feed circuits (542) with the test light.

Is the test light ON for both terminals?

--

Go to Step 9

Go to Step 10

8

  1. Connect a test light to ground.
  2. Remove the cooling fan relay. Refer toA/C Compressor and Cooling Fan Relays Replacement .
  3. Probe the cooling fan motor battery feed circuit (409) with the test light.

Does the test light illuminate?

--

Go to Step 12

Go to Step 13

9

Connect a fused jumper wire between the following circuits:

    • Cooling fan relay battery feed (542)
    • Cooling fan motor battery feed (409)

Is the cooling fan ON?

--

Go to Step 14

Go to Step 15

10

  1. Check the ignition feed circuit(s) to cooling fan relay terminal 87 for the following conditions:
    2. • Short to ground
    • Open circuit(s)
  2. Repair the circuit(s) as necessary. Refer to Wiring Repairs in Wiring Systems.

Was repair necessary?

--

Go to Step 27

Go to Step 11

11
  1. Disconnect the cooling fan motor electrical connector.
  2. Connect the test light to B+.
  3. Probe the Cooling fan Relay Terminal 87 with the test light.

Does the light illuminate?

--

Go to Step 25

Go to Step 23

12

Repair the short to B+ in the cooling fan motor battery feed circuit (409). Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 27

--

13
  1. Connect a test light to B+.
  2. Probe the cooling fan control circuit (335) with the test light.

Does the test light illuminate?

--

Go to Step 16

Go to Step 24

14

  1. Connect a test light to B+.
  2. Probe the cooling fan control circuit (335) with the test light.
  3. Command ON the cooling fan with the scan tool.

Does the test light illuminate?

--

Go to Step 17

Go to Step 18

15

  1. Fused jumper wire still in place.
  2. Disconnect the cooling fan electrical connector.
  3. Connect a test light to ground.
  4. Probe the cooling fan circuit (409) terminal B with the test light.

Does the test light illuminate?

--

Go to Step 19

Go to Step 20

16
  1. Turn OFF the ignition switch.
  2. Repair the short to ground in the cooling fan control circuit (335). Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 27

--

17
  1. Check the terminals to the cooling fan relay.
  2. Repair the terminals as necessary. Refer to Connector Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 27

Go to Step 24

18
  1. Check the cooling fan control circuit (335) for the following conditions:
    2. • Open circuit
    • Short to B+
    • Poor electrical terminal connections
  2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 27

Go to Step 26

19
  1. Connect the test light to B+.
  2. Probe the cooling fan ground circuit (151) with the test light.

Does the test light illuminate?

--

Go to Step 21

Go to Step 22

20
  1. Turn OFF the ignition switch.
  2. Check the cooling fan motor ignition feed circuit (409) for the following conditions:
    3. • Poor electrical terminal connection
    • Open circuit
  3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 27

--

21
  1. Check for poor electrical terminal connections at the cooling fan electrical connector.
  2. Repair the connections as necessary. Refer to Connector Repairs in Wiring Systems.

Was a repair necessary.

--

Go to Step 27

Go to Step 23

22
  1. Turn OFF the ignition switch.
  2. Check the cooling fan ground circuit (151) for the following condition(s):
    3. • Poor electrical connection
    • Open circuit
  3. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 27

--

23

Replace the cooling fan motor. Refer to Engine Cooling Fan Replacement in Engine Cooling.

Is the action complete?

--

Go to Step 27

--

24
  1. Turn OFF the ignition switch.
  2. Replace the cooling fan relay. Refer to A/C Compressor and Cooling Fan Relays Replacement .

Is the action complete?

--

Go to Step 27

--

25

Repair the short to ground in the cooling fan motor battery feed circuit (circuit 409). Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 27

--

26

  1. Turn OFF the ignition switch.
  2. Replace the PCM. Refer to PCM Replacement .

Is the action complete?

--

Go to Step 27

--

27

  1. Turn ON the ignition switch leaving the engine OFF.
  2. Command ON the cooling fan with the scan tool.

Does the cooling fan turn ON when commanded with the scan tool?

--

System OK

Go to Step 2