GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The Secondary Air Injection (AIR) System is designed to lower exhaust emission levels during a cold or warm start. The AIR pump is timed to remain ON for approximately one minute after the engine is started.

The powertrain control module (PCM) commands the AIR pump relay ON by supplying a ground on the control circuit. This action energizes the AIR pump, forcing air into the exhaust stream. The PCM also commands the AIR vacuum control solenoid valve ON which applies vacuum to the AIR shut-off valve. When vacuum is applied to the AIR shut-off valve, airflow from the AIR pump flows through the hoses/pipes and to the exhaust check valves. The air then enters into the exhaust stream. The air that is introduced into the exhaust system accelerates catalyst operation by decreasing the time it takes for the convertor to begin its process of burning the incomplete gases; reducing engine exhaust emission levels. When inactive, the check valves and the shut-off valve prevent airflow in either direction.

The PCM detects a system airflow problem by monitoring the heated oxygen sensors (HO2S) and short term fuel trim during normal Open Loop AIR system operation. This is called a passive test. If the passive test indicates a pass, the PCM takes no further action. If the passive test fails or is inconclusive, the diagnostic will proceed with an intrusive or active tests. The PCM will command the AIR system ON during Closed Loop operation under normal operating conditions. The active test will pass or fail based on the response from the HO2S. A lean HO2S response indicates that the secondary AIR system is functioning normally. An increasing short term fuel trim value also indicates a normally functioning system. The AIR diagnostic consists of the passive test and the active tests. The AIR diagnostic requires failure of the passive and active tests on two consecutive key cycles to illuminate the malfunction indicator lamp (MIL) and store a DTC. If the PCM detects that the HO2S and short term FT did not respond as expected on one of the engine banks, DTC P1415 or P1416 sets. If the PCM detects that the HO2S and short term FT did not respond as expected on both of the engine banks, DTC P0410 sets.

Conditions for Running the DTC

    • DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0155, P0171, P0172, P0174, P0175, P0300, P0440, P0442, P0446, P0506, or P0507 are not set.
    • The engine run time is more than 15 seconds after Closed Loop operation.
    • The engine load is less than 33 percent.
    • The engine air flow is less than 18 g/s.
    • The engine speed is more than 750 RPM.
    • The ignition voltage is more than 11.7 volts.
    • The engine coolant temperature (ECT) is 70-110°C (158-230°F).
    • The intake air temperature (IAT) is more than 2°C (36°F).
    • The fuel system is not operating in power enrichment or deceleration fuel cut-off (DFCO).
    • The short term fuel trim is between +5 and -5 percent.
    • The startup ECT is below 80°C (176°F).
    • The vehicle speed is more than 25 km/h (15 mph).

Conditions for Setting the DTC

    • The HO2S voltage does not decrease to less than 222 mV within 1.2 seconds when the AIR pump turns on during Closed Loop operation.
        AND
    • Short term fuel trim does not increase above a predetermined amount.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

    • Using Freeze Frame/Failure Records may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records can aid in determining how many miles the vehicle has been driven since the DTC set. The Fail Counter and Pass Counter can also aid in determining how many ignition cycles the diagnostic reported a pass or a fail. Operate the vehicle within the same Freeze Frame conditions, such as RPM, load, vehicle speed, temperature etc., that you observed. This will isolate when the DTC failed.
    • An intermittent may be caused by any of the following conditions:
       - Low system air flow may cause this DTC to set.
       - Excessive exhaust system back pressure
       - Moisture, water, or debris ingested into the AIR pump
       - Pinched, kinked, heat damaged, or deteriorated hoses or vacuum hoses
       - Restriction in the pump inlet, duct, or filter
    • Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
    • For an intermittent, refer to Intermittent Conditions .
    • When commanding the AIR system ON with a scan tool, the PCM will activate the AIR pump and the AIR solenoid. The fuel control system will then enter an Open Loop status. This action will allow fresh air to enter the exhaust stream and cause the HO2S mV parameters to drop to near 0 mV. This would indicate a properly operating system. However, if the AIR pump does not operate, or there is no air flow from the pump entering the exhaust stream due to a leak in the system, the HO2S parameter may still drop below 100 mV. This is due to fresh air being drawn into the exhaust stream from the check valve operation and the opening of the shut-off valve. The HO2S will respond with a drop in mV readings as a result of this air leaning out the exhaust gases. The voltages may drop below 100 mV, but not approach the near 0 mV parameter.
    • An AIR pump which exhibits an exhaust noise through the pump may have an AIR solenoid or AIR shut-off valve stuck open. The short term fuel trims may indicate a higher than normal value. This condition may not set a DTC P0410.
    • An AIR shut-off valve that has become inoperative and has shown indications of exhaust gases in the outlet port, or heat damaged hoses may indicate an exhaust check valve failure.
    • The vacuum lines at the vacuum solenoid cannot be reversed. This condition may hold the shut-off valve open continually. The center port of the vacuum solenoid is the vacuum source.
    • A vacuum solenoid leaking vacuum will hold the shut-off valve open. An exhaust noise may be heard through the air cleaner. Fuel trim values may also indicate a higher than normal value at idle. This DTC may not set.
    • Leaking check valves will leave traces of exhaust carbon in the AIR system, with a possibility of heat damage to the hoses and shut-off valve.

Test Description

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

  1. This step will determine if the AIR system is functioning correctly.

  2. This step determines if there is a short to voltage on the AIR pump supply voltage circuit. Allowing the AIR pump to operate continuously.

  3. This step is to test for a short to voltage on the AIR solenoid supply voltage circuit keeping the AIR solenoid ON at all times.

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition , with the engine OFF.
  2. Listen for AIR pump operation.

Does the secondary air injection (AIR) pump run constantly?

--

Go to Step 16

Go to Step 3

3

  1. Turn ON the ignition, with the engine OFF.
  2. Command the AIR pump relay ON and OFF with a scan tool.
  3. Listen for AIR pump operation.

Does the AIR pump turn ON and OFF when commanded with a scan tool?

--

Go to Step 4

Go to Step 6

4

  1. Allow the engine to reach operating temperature.
  2. Ensure Closed Loop is achieved.
  3. Command the AIR pump relay ON with a scan tool.
  4. Observe HO2S 1 bank   1 and HO2S   1 bank  2 voltage parameters.

Do the HO2S  1 bank  1 and HO2S  1 bank  2 voltage parameters decrease to the specified value within six seconds?

100 mV

Go to Step 14

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Remove the vacuum hose at the AIR shut-off valve.
  3. Connect a vacuum pump to the AIR shut-off valve and apply 10  inches of mercury, 254 mm of mercury to the AIR shut- off valve.

Does the AIR shut-off valve hold vacuum for the specified amount?

30 seconds.

Go to Step 15

Go to Step 53

6

  1. Turn ON the ignition, with the engine OFF.
  2. Disconnect the AIR pump connector.
  3. Probe the AIR pump supply voltage circuit at the AIR pump connector with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors .
  4. Command the AIR Pump relay ON and OFF with a scan tool.

Does the test lamp turn ON and OFF when commanded with a scan tool?

--

Go to Step 11

Go to Step 7

7

  1. Locate the AIR fuse block and remove the cover. Refer to Engine Controls Component Views .
  2. Inspect the AIR pump fuse.

Is the fuse open?

--

Go to Step 26

Go to Step 8

8

  1. Remove the AIR pump relay. refer to Relay Replacement in Wiring Systems.
  2. Probe the AIR pump relay battery positive voltage circuit, switched side, of the relay at the AIR fuse block with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors .

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 47

9

  1. Turn the ignition to the ON position.
  2. Probe the AIR pump relay ignition 1 voltage circuit, coil side, at the AIR fuse block with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors .

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 33

10

  1. Probe the AIR pump relay control circuit, at the AIR fuse block with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors .
  2. Command the AIR pump relay ON and OFF.

Does the test lamp turn ON and OFF when commanded with a scan tool?

--

Go to Step 40

Go to Step 31

11

Important: The DMM and test leads must be calibrated to 0   ohms in order to prevent misdiagnosis. Refer to the DMM User Manual for calibration procedure.

Measure the resistance of the AIR pump ground circuit with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the resistance within the specified range?

0-3  ohms.

Go to Step 12

Go to Step 50

12

Important: Ensure that the fuse rating does not exceed the load rating of the jumper wire.

  1. Turn OFF the ignition.
  2. Locate the AIR fuse block and remove the AIR pump relay. Refer to Engine Controls Component Views and Relay Replacement in Wiring Systems.
  3. Connect a 30- amp fused jumper wire between the battery positive voltage circuit and the AIR pump supply voltage circuit at the AIR fuse block.

Does the AIR pump turn ON?

--

Go to Step 40

Go to Step 13

13

Important: The DMM and test leads must be calibrated to 0   ohms in order to prevent misdiagnosis. Refer to the DMM User Manual for calibration procedure.

Measure the resistance of the AIR pump supply voltage circuit with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the resistance within the specified range?

0-3  ohms.

Go to Step 41

Go to Step 48

14

  1. Remove the vacuum hose from AIR shut-off valve.
  2. Connect a vacuum gage to the vacuum hose.
  3. Start and idle the engine.

Is the vacuum equal to the specified value?

0 in Hg/0 mm Hg

Go to Step 39

Go to Step 25

15

  1. Remove the vacuum pump from the AIR shut-off valve.
  2. Connect a vacuum gage to the vacuum hose.
  3. Start and idle the engine.
  4. Command the AIR pump relay ON with a scan tool.

Does the vacuum increase to more than the specified value?

10 in Hg/254 mm Hg

Go to Step 32

Go to Step 18

16

  1. Remove the AIR pump relay. Refer to Relay Replacement in Wiring Systems.
  2. Listen for AIR pump operation.

Does the AIR pump operate constantly?

--

Go to Step 49

Go to Step 17

17

Probe the AIR pump relay control circuit at the AIR connector with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 24

Go to Step 52

18

  1. Remove the vacuum hose from the outlet port of the AIR solenoid.
  2. Connect a vacuum gage to the AIR solenoid outlet port.
  3. Start and idle the engine.
  4. Command the AIR pump relay ON and OFF.

Does the vacuum displayed on the gage increase to more than the specified amount when commanded ON and drop back to zero inches of Hg when commanded OFF?

10 in Hg/254 MM of Hg

Go to Step 36

Go to Step 19

19

  1. Remove the vacuum supply hose at the AIR solenoid inlet port.
  2. Connect a vacuum gage to the vacuum supply hose.
  3. Start and idle the engine.

Is the vacuum more than the specified value?

10 in Hg/254 MM Hg

Go to Step 21

Go to Step 20

20

  1. Remove the vacuum hose from the vacuum supply fitting at the intake manifold.
  2. Connect a vacuum gage to the vacuum fitting.
  3. Start and idle the engine.

Is the vacuum more than the specified value?

10 in Hg/254 MM Hg

Go to Step 36

Go to Intake Manifold Cleaning and Inspection In Unit Repair

21

  1. Disconnect the AIR solenoid connector.
  2. Probe the AIR solenoid supply voltage circuit with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors .
  3. Command the AIR pump relay ON and OFF with a scan tool.

Does the test lamp turn ON and OFF when commanded with a scan tool?

--

Go to Step 22

Go to Step 23

22

Probe the AIR solenoid ground circuit with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors .

Does the test lamp illuminate?

--

Go to Step 42

Go to Step 49

23

Inspect the AIR solenoid fuse at the AIR Fuse block. Refer to Engine Controls Component Views .

Is the AIR solenoid fuse open?

--

Go to Step 34

Go to Step 44

24

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

Did you find and correct a condition?

--

Go to Step 58

Go to Step 43

25

  1. Test the AIR solenoid supply voltage circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. If you find a condition replace the AIR solenoid fuse as necessary.

Did you find and correct a condition?

--

Go to Step 58

Go to Step 54

26

  1. Test the battery positive voltage circuit between the AIR fuse and the AIR pump relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Replace the AIR fuse as necessary.

Did you find and correct the condition?

--

Go to Step 58

Go to Step 27

27

  1. Test the AIR pump supply voltage circuit between the AIR pump relay and the AIR pump for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  2. Replace the AIR fuse as necessary.

Did you find and correct a condition?

--

Go to Step 57

Go to Step 28

28

  1. Remove the air inlet hose from the AIR pump.
  2. Inspect for water intrusion on the inlet side of the AIR pump.

Is water contamination found on the inlet side of the AIR pump?

--

Go to Step 46

Go to Step 29

29

  1. Remove the outlet hose from the AIR pump.
  2. Remove the AIR pump without turning it over to avoid losing any water contamination. Refer to Secondary Air Injection Pump Replacement .
  3. Inspect for water intrusion on the outlet side of the AIR pump. Pour the water sample into a clear container.

Is water contamination found on the outlet side of the AIR pump?

--

Go to Step 35

Go to Step 30

30

  1. Connect the AIR pump connector.
  2. Secure the AIR pump
  3. Replace the AIR pump fuse as necessary.
  4. Install the AIR pump relay.
  5. Turn the ignition ON, with the engine OFF.
  6. Command the AIR pump relay ON with a scan tool.
  7. Listen for AIR pump operation.

Does the AIR pump operate?

--

Go to Intermittent Conditions

Go to Step 56

31

Test the AIR pump relay control circuit for an open or short to voltage Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 58

Go to Step 43

32

  1. Remove the AIR crossover hose at the right side exhaust check valve.
  2. Start and idle the engine.
  3. Command the AIR pump relay ON with a scan tool.

Is a pressurize airflow present at the crossover hose?

--

Go to Step 38

Go to Step 37

33

  1. Test the ignition  1 voltage circuits supplied by the IGN  E fuse for an open or short to ground. Refer to Wiring Repairs and Circuit Testing in Wiring Systems.
  2. Replace fuse E as necessary.

Did you find and correct a condition?

--

Go to Step 58

Go to Intermittent Conditions

34

  1. Test the AIR solenoid supply voltage circuit for a short to ground. Refer to Wiring Repairs and Circuit Testing in Wiring Systems.
  2. Replaced the AIR solenoid fuse as necessary.

Did you find and correct a condition?

--

Go to Step 58

Go to Step 54

35

Inspect the water sample taken from the outlet side of the AIR pump.

Does the water sample have a yellow tint and an exhaust odor?

--

Go to Step 51

Go to Step 45

36

Inspect the following components for a leak or restriction.

    • Vacuum Hoses.
    • Vacuum Check valve.

Did you find and correct a condition?

--

Go to Step 58

Go to Intermittent Conditions

37

Inspect the following components for a leak or restriction.

    • The AIR pump inlet hose.
    • The AIR pump outlet hose
    • The AIR pump crossover hoses
    • The plastic tee connector in the AIR crossover hose.
    • The AIR shut-off valve.

Did you find and correct a condition?

--

Go to Step 58

Go to Step 56

38

Inspect the following components for a leak or restriction.

    • AIR exhaust check valves.
    • AIR exhaust check valve outlet tubes.
    • The exhaust manifold

Did you find and correct a condition?

--

Go to Step 58

Go to Intermittent Conditions

39

Connect a vacuum pump to the AIR shut-off valve and apply 10   inches of vacuum to the AIR shut- off valve.

Does the AIR shut-off valve hold vacuum for the specified amount?

30   seconds

System OK

Go to Step 53

40

Test for an intermittent and for a poor connection at the AIR pump relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 58

Go to Step 52

41

Test for an intermittent and for a poor connection at the AIR pump connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 58

Go to Step 56

42

Test for and intermittent and for a poor connection at the AIR solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 58

Go to Step 54

43

Test for shorted terminals and poor connections at the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 58

Go to Step 57

44

Test the AIR solenoid supply voltage circuit for an open or high resistance. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

--

Go to Step 58

Go to Intermittent Conditions

45

  1. Remove the AIR solenoid.
  2. Inspect the AIR solenoid for water intrusion.

Is water contamination found on the outlet side of the AIR solenoid?

--

Go to Step 55

Go to Step 51

46

Inspect the AIR inlet hose for the following conditions.

    • Proper routing.
    • Damage

Did you find a condition?

--

Go to Step 56

Go to Intermittent Conditions

47

Repair the open or high resistance in the battery positive voltage circuit to the AIR pump relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 58

--

48

Repair the high resistance in the AIR pump supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 58

--

49

Repair the short to voltage in the AIR pump supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 58

--

50

Important: The AIR pump and AIR solenoid have a shared ground circuit.

Repair the open or high resistance in the AIR pump ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 58

--

51

Replace the AIR Exhaust Check valves. Refer to Secondary Air Injection Check Valve and Check Valve Pipe Replacement - Bank 1 and Secondary Air Injection Check Valve and Check Valve Pipe Replacement - Bank 2 .

Did you complete the replacement?

--

Go to Step 56

--

52

Replace the AIR pump relay. Refer to Electrical Center Identification Views in Wiring Systems.

Did you complete the replacement?

--

Go to Step 58

--

53

Replace the AIR shut off valve. Refer to Secondary Air Injection Shut Off Valve Replacement .

Did you complete the replacement?

--

Go to Step 59

--

54

Replace the AIR solenoid. Refer to Secondary Air Injection Solenoid Valve Replacement .

Did you complete the replacement?

--

Go to Step 58

--

55

Important: Ensure the correct routing of the AIR hoses. The inlet side of the AIR pump is marked IN.

  1. Replace the AIR solenoid. Refer to Secondary Air Injection Solenoid Valve Replacement .
  2. Replace the AIR pump. Refer to Secondary Air Injection Shut Off Valve Replacement .

Did you complete the replacements?

--

Go to Step 58

--

56

Important: Ensure the correct routing of the AIR hoses. The inlet side of the AIR pump is marked IN.

Replace the AIR pump. Refer to Secondary Air Injection Shut Off Valve Replacement .

Did you complete the replacement?

--

Go to Step 58

--

57

Important: The replacement control module must be programmed.

Replace the control module.

Did you complete the replacement?

--

Go to Step 58

--

58

  1. Ensure all components and connectors are installed and secured.
  2. Command the AIR pump ON and OFF with a scan tool.
  3. Listen for AIR pump operation.

Does the AIR pump turn ON and OFF?

--

Go to Step 59

Go to Step 2

59

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30   seconds.
  3. Start the engine.
  4. Operate vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the Conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 2

Go to Step 60

60

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK