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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Restraints 🢒 SIR 🢒 DTC P0480, P0481, or P0482

DTC P0480, P0481, or P0482 2.0L (LSJ)

Circuit Description

The powertrain control module (PCM) controls the low speed cooling fan operation by grounding the cool fan 1 relay control circuit with an internal solid state device called a driver. For high speed cooling fan operation, the PCM grounds the cool fan 2 and S/P relay control circuit at the same time the cool fan 1 control circuit is grounded. Battery positive voltage is supplied to the cool fan 1, cool fan 2 and S/P fan relays. When the PCM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the PCM is commanding a fan relay OFF, the voltage potential of the control circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the DTC will set.

The PCM will monitor the control circuit for the following conditions:

    • A short to ground
    • A short to voltage
    • An open circuit
    • An open relay coil
    • An internally shorted or excessively low resistance relay coil

When the PCM detects any of the above conditions, the DTC will set and the affected driver will be disabled.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC P0480 Cooling Fan Relay 1 Control Circuit
    • DTC P0481 Cooling Fan Relay 2 Control Circuit
    • DTC P0482 Cooling Fan Relay 3 Control Circuit

Conditions for Running the DTC
    • The ignition is ON.
    • System voltage is between 9-18 volts.
    • The relay control circuit transitions from OFF to ON or ON to OFF.

Conditions for Setting the DTC
    • The PCM detects an open, a short to ground, or a short to voltage on the cooling fan relay control circuit.
    • The above conditions are present for at least 30 seconds.

Action Taken When the DTC Sets
    • The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
    • The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

Conditions for Clearing the MIL/DTC
    • The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
    • The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool.

Diagnostic Aids
    • If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • Review the Freeze Frame/Failure Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Listen for an audible click when the cool fan 1 relay operates.

    2.

  2. Listen for an audible click when the cool fan 2 and cool fan S/P relays operate.

    3.

  3. This step tests for voltage at the coil side of the cool fan 1 relay. The COOL FAN 1 fuse supplies battery positive voltage to the coil side of the cool fan 1 relay.

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Ground the low speed relay control circuit C1 pin 51 of the powertrain control module (PCM).
  2. Turn ON the ignition, with the engine OFF.

Does the cool fan 1 relay turn ON and OFF with each command?

Go to Step 3

Go to Step 4

3

Ground the high speed relay control circuit C1 pin 10 of the PCM.

Do the cool fan S/P and the cool fan 2 relays turn ON?

Go to Diagnostic Aids

Go to Step 6

4

  1. Turn OFF the ignition.
  2. Disconnect the cool fan 1 relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the cool fan 1 relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 16

5

  1. Connect a test lamp between the control circuit of the cool fan 1 relay and the battery positive voltage circuit of the cool fan 1 relay.
  2. Ground the low speed relay control circuit.

Does the test lamp turn ON?

Go to Step 12

Go to Step 9

6

  1. Turn OFF the ignition.
  2. Disconnect the cool fan 2 relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the cool fan 2 relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 16

7
  1. Connect a test lamp between the control circuit of the cool fan S/P relay and the battery positive voltage circuit of the cool fan S/P relay.
  2. Ground the high speed relay control circuit.

Does the test lamp turn ON?

Go to Step 14

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Disconnect the cooling fan S/P relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the control circuit of the cool fan S/P relay and the battery positive voltage circuit of the cool fan S/P relay.
  5. Ground the high speed relay control circuit.

Does the test lamp turn ON?

Go to Step 13

Go to Step 9

9

Does the test lamp remain illuminated when the appropriate control circuit is grounded and then not grounded.

Go to Step 11

Go to Step 10

10

Test the control circuit of the appropriate relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 15

11

Test the control circuit of the appropriate relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 21

Go to Step 15

12

Inspect for poor connections at the cool fan 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 21

Go to Step 17

13

Inspect for poor connections at the cool fan S/P 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 21

Go to Step 18

14

Inspect for poor connections at the cool fan relay 2. 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 21

Go to Step 19

15

Inspect for poor connections at the harness connector of the PCM. 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 21

Go to Step 20

16

Repair the battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 21

--

17

Replace the cool fan 1 relay.

Did you complete the replacement?

Go to Step 21

--

18

Replace the cool fan S/P relay.

Did you complete the replacement?

Go to Step 21

--

19

Replace the cool fan 2 relay.

Did you complete the replacement?

Go to Step 21

--

20

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 21

--

21
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK

DTC P0480, P0481, or P0482 2.2L (L61)

Circuit Description

The cooling fan has 2 windings in the motor, one winding is for low speed and the other winding is for high speed. The engine control module (ECM) controls the low speed fan operation by grounding the cool fan 1 relay control circuit. When the cooling fan 1 relay is energized, voltage is delivered to the cooling fan low speed winding. The ECM controls the high speed fan operation by grounding the cool fan 2 relay control circuit. When the cooling fan 2 relay is energized, voltage is delivered to the cooling fan high speed winding. The ECM controls the cooling fan relays by grounding the cooling fan relay control circuit through an internal solid state device called a driver. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component ON, the voltage potential of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the DTC will set.

The ECM will monitor the control circuit for the following conditions:

    • A short to ground
    • A short to voltage
    • An open circuit
    • An open relay coil
    • An internally shorted or excessively low resistance relay coil.

When the ECM detects any of the above conditions, the DTC will set and the affected driver will be disabled.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • P0480 is for the low speed cooling fan relay control circuit.
    • P0481 is for the high speed cooling fan relay control circuit.
    • P0482 Is for the cooling fan relay control circuit.

Conditions for Running the DTC
    • The ignition is ON.
    • The battery voltage is more than 9 volts.

Conditions for Setting the DTC
    • The ECM detects an open, a short to ground, or a short to voltage on the cooling fan relay control circuit.
    • The condition must be present for a minimum of 6 seconds.

Action Taken When the DTC Sets
    • The ECM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
    • The ECM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

Conditions for Clearing the MIL/DTC
    • The ECM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
    • The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using the scan tool.

Diagnostic Aids
    • If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • Review the Freeze Frame/Failure Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Listen for an audible click when the cooling fan 1 relay operates.

    2.

  2. Listen for an audible click when the cooling fan 2 relay operates.

    3.

  3. This step tests for voltage at the coil side of the cooling fan 1 relay. The cool fan 1 fuse supplies power to the cooling fan 1 relay.

    4.

  4. This step tests for voltage at the coil side of the cooling fan 2 relay. The cool fan 2 fuse supplies power to the cooling fan 1 relay.

    5.

  5. This step verifies that the ECM is providing ground to the cooling fan relay.

    6.

  6. This step tests if ground is constantly being applied to the cooling fan relay.

Step

Action

Yes

No

Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Ground the low speed cooling fan relay control C1 pin 43 of the engine control module (ECM).
  2. Turn ON the ignition, with the engine OFF.

Does the cooling fan 1 relay turn ON?

Go to Step 3

Go to Step 4

3

  1. Ground the high speed cooling fan relay control C2 pin 47 of the ECM.
  2. Turn ON the ignition, with the engine OFF.

Does the cooling fan 2 relay turn ON?

Go to Diagnostic Aids

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Disconnect the cooling fan 1 relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the cooling fan 1 relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 10

5

  1. Turn OFF the ignition.
  2. Disconnect the cooling fan 2 relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the cooling fan 2 relay with a test lamp that is connected the a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 10

6

  1. Connect a test lamp between the control circuit of the appropriate cooling fan relay and the battery positive voltage circuit of the appropriate cooling fan relay.
  2. Ground the appropriate cooling fan relay control circuit of the ECM.

Does the test lamp turn ON?

Go to Step 12

Go to Step 7

7

Does the test lamp remain illuminated when the appropriate relay control circuit is grounded and then not grounded?

Go to Step 9

Go to Step 8

8

Test the control circuit of the appropriate cooling fan relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 11

9

Test the control circuit of the appropriate cooling fan relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 11

10

Test the battery positive voltage circuit of the appropriate cooling fan relay for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

Go to Step 13

11

Inspect for poor connections at the harness connector of the engine control module (ECM). 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 16

Go to Step 15

12

Inspect for poor connections at the appropriate cooling fan 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 16

Go to Step 14

13

Repair the cooling fan motor supply voltage circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

--

14

Replace the appropriate cooling fan relay.

Did you complete the replacement?

Go to Step 16

--

15

Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 16

--

16
  1. Use the scan tool in order to clear the DTCs .
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK