Circuit Description
The purpose of the Secondary Air Injection (AIR) system is to reduce the Hydrocarbon (HC), the Carbon Monoxide (CO), and the Oxides of Nitrogen (NOx) exhaust emissions by causing any combustible gases in the exhaust to re-burn. This also causes the catalytic converters and the heated oxygen sensors to reach the normal operating temperatures more quickly, thus the Closed Loop operation occurs earlier.
When the engine is started, the ECM commands the AIR pump relay and the AIR Cutoff Valve Vacuum Control solenoid on, injecting clean air into the engine exhaust ports. The ECM switches the AIR system off when the oxygen sensors become active. The AIR Cutoff Valve prevents air from being drawn into the system when the AIR pump is off. The vacuum to the valve is controlled by the AIR Cutoff Valve Vacuum Control solenoid. A check valve close to the engine prevents hot exhaust gases from backing up into the AIR system.
The AIR Cutoff Valve Vacuum Control solenoid is supplied power via the Engine Controls Power Relay (Switched B+). The Engine Control Module (ECM) controls the solenoid by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component on, the voltage 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, this DTC will set.
Conditions for Running the DTC
Tested continuously
Conditions for Setting the DTC
A short to ground, an open circuit, or a short to battery voltage detected on the control circuit.
Action Taken When the DTC Sets
The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.
Conditions for Clearing the MIL/DTC
| • | The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes. |
| • | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic. |
| • | The ECM battery voltage is interrupted. |
| • | The scan tool clears the MIL/DTC. |
Diagnostic Aids
Use the Connector Test Adapter Kit J 35616 for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.
Check for the following conditions:
| • | Poor connections at the ECM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Electrical Diagnosis in Engine Electrical, Troubleshooting Procedures, Checking Terminal Contact for proper procedure. |
| • | Misrouted harness. Inspect the harness in order to ensure that the harness is not routed too close to any high voltage wires such as spark plug leads, or too close to any high current devices such as the alternator, the motors, the solenoids, etc. |
| • | Damaged harness. Inspect the wiring harness for any damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault. |
Refer to Symptoms for the Intermittents.
Test Description
The number(s) below refer to the step numbers on the diagnostic table.
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Listen for an audible click when the solenoid operates. Repeat the commands as necessary.
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This check can detect a partially shorted coil which would cause excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When warm the coil may open (the amps drop to 0), or short (above 750 mA).
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If no trouble is found in the control circuit or the connection at the ECM, the ECM may be damaged, however, this is an extremely unlikely failure.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System check? | -- | ||
Does the solenoid turn ON and OFF with each command? | -- | |||
Does the current draw measure within the specified range? | 100 - 750 mA | Refer to Diagnostic Aids | ||
4 |
The DMM should display an infinite resistance. Does the DVM display an infinite resistance? | -- | ||
5 |
Does the test lamp turn ON and OFF with each command? | -- | ||
6 | Probe the Switched B+ circuit in the solenoid harness connector with the test lamp connected to ground. The test lamp should illuminate. Does the test lamp illuminate? | -- | ||
7 |
Does the solenoid operate? | -- | ||
8 | Test for a poor connection or poor terminal tension at the solenoid harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a repair is necessary refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
9 | Repair the solenoid control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
10 | Repair the Switched B+ circuit to the solenoid. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
11 | Replace the solenoid, refer to Secondary Air Cutoff Valve Vacuum Solenoid Replacement . Is the action complete? | -- | -- | |
12 | Test for a poor connection or poor terminal tension at the ECM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a repair is necessary refer to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
|
Important: This vehicle is equipped with a Theft Deterrent System which interfaces with the Engine Control Module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle. Replace the ECM. Refer to Engine Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
14 |
Is this DTC set? | -- | ||
15 | Were there any additional DTCs noted during the Powertrain OBD System Check that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
