Circuit Description
The powertrain control module (PCM) activates the secondary air injection (AIR) system by grounding the AIR relay. This energizes the pump and the vacuum control solenoid. As vacuum is applied to the 2 shut-off valves, fresh air is allowed to pass through them. The AIR pump forces fresh air past the shut-off valves and into the exhaust stream in order to accelerate catalyst operation. The PCM will run up to 3 diagnostic tests using the oxygen sensors (O2S) 1 voltage and short term FT to verify system operation. The system can be diagnosed during normal secondary air injection operation or the scan tool can activate the system specifically for diagnostic purposes. If an air flow problem is detected this diagnostic trouble code (DTC) will set. When inactive, the shut-off valve prevents air flow in either direction.
Conditions for Running the DTC
| • | DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0133, P0134, P0171, P0172, P0177, P0178, P0179, P0300, P0301-P0304, P0336, P0341, P0506, P0507, P0601, or P1133 are not set. |
| • | The AIR system is commanded ON for more than 20 seconds. |
| • | The intake air temperature (IAT) is between 1-151°C (32-302°F). |
| • | The engine coolant temperature (ECT) is between 5-114°C (41-230°F). |
| • | The battery voltage is more than 11.7 volts. |
| • | The battery voltage is more than 11.7 volts. |
| • | The engine run time is more than 200 seconds. |
| • | The calculated air flow is more than 11 gps. |
| • | The accumulated flow more than 240 cts. |
| • | A fuel trim cell of 16 or 17. |
| • | The long term fuel trim is between -3 and +4 |
| • | The base pulse width is more than 1.2 ms |
| • | The throttle position (TP) sensor changes less than 5 percent. |
| • | Stabilization time of more than 1 second. |
Conditions for Setting the DTC
Lean time is more than 1 second during 4 second active test.
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
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly check 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.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step checks for a restriction in the engine vacuum supply to the AIR shut-off valve.
-
This step determines if the lack of air is caused by an open in the AIR supply hose or a defective shut-off valve.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 | Start the engine. Does the AIR pump run constantly? | -- | Go to Step 3 | Go to Step 4 |
3 |
Is the test lamp illuminated? | -- | Go to Step 17 | Go to Step 23 |
4 |
Does the AIR pump turn ON? | -- | Go to Step 11 | Go to Step 5 |
5 |
Is the test lamp illuminated? | -- | Go to Step 6 | Go to Step 18 |
6 | Probe the AIR pump relay B+ supply circuit terminal (control side of relay) using the test lamp connected to ground. Is the test lamp illuminated? | -- | Go to Step 7 | Go to Step 20 |
7 |
Is the test lamp illuminated? | -- | Go to Step 8 | Go to Step 21 |
8 |
Is the test lamp illuminated? | -- | Go to Step 9 | Go to Step 24 |
9 |
Is the test lamp illuminated? | -- | Go to Step 10 | Go to Step 24 |
10 | Probe terminal B of the C2 connector with a test lamp connected to B+. Is the test lamp illuminated? | -- | Go to Step 25 | Go to Step 19 |
11 |
Does the Short Term FT increase by the minimum specified amount in the time given? | 12% in 6 seconds | Go to Diagnostic Aids | Go to Step 12 |
12 |
Is the test lamp illuminated? | -- | Go to Step 13 | Go to Step 19 |
13 |
Is the test lamp illuminated? | -- | Go to Step 14 | Go to Step 22 |
Is near engine idle vacuum displayed on the vacuum gauge? | -- | Go to Step 15 | Go to Step 26 | |
Is air pressure from the AIR pump present at the AIR hose outlet? | -- | Go to Diagnostic Aids | Go to Step 16 | |
16 |
Is air pressure present at the outlet of the AIR shut-off valve? | -- | Go to Step 27 | Go to Step 28 |
17 | Repair the short to ground in the AIR relay control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 30 | -- |
18 | Repair the open circuit or short to ground between the battery supply and the AIR relay. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 30 | -- |
19 | Repair the faulty ground connection or the open ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 30 | -- |
20 | Repair the open circuit between the IGN E fuse and the AIR pump relay. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 30 | -- |
21 | Repair the open in the relay control circuit between the PCM and the relay. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 30 | -- |
22 |
Is the reading within the specification? | 0-2 ohms | Go to Step 24 | Go to Step 23 |
23 | Replace the AIR pump relay. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 30 | -- |
24 | Repair the open in the battery supply from the AIR relay to the AIR pump/solenoid. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 30 | -- |
25 |
Did you find and correct the condition? | -- | Go to Step 30 | Go to Step 29 |
26 |
Important: Inspect the vacuum check valve for proper installation. The tapered side of the check valve goes toward the vacuum source. Also inspect for vacuum with the check valve removed from the vacuum line. If there is vacuum replace the check valve. If vacuum is present to the solenoid, replace the AIR solenoid. Repair the vacuum restriction to the AIR shut-off valve. Is the action complete? | -- | Go to Step 30 | -- |
27 | Repair the open/restriction in the AIR hose between the AIR pump shut-off valve and the AIR exhaust check valve. Is the action complete? | -- | Go to Step 30 | -- |
28 | Check for a restriction in the AIR intake hose. If no restriction is found, replace the AIR shut-off valve. Is the action complete? | -- | Go to Step 30 | -- |
29 | Replace the AIR pump. Refer to Secondary Air Injection Pump Replacement . Is the action complete? | -- | Go to Step 30 | -- |
30 |
Does the DTC run and pass? | -- | Go to Step 31 | Go to Step 2 |
31 | With a scan tool, observe the stored information in Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
