Secondary Air Injection System Diagnosis

Circuit Description
A fused ignition voltage is supplied to the AIR Pump Relay. The VCM controls the AIR Pump by grounding the AIR Pump Relay Control circuit. This energizes the relay and supplies voltage to the AIR Pump clutch. When the fuel system goes into Closed Loop, the VCM opens the ground to the AIR Pump Relay Control circuit.

Diagnostic Aids
An AIR Pump that is stuck on could cause a fuel trim lean code.

The AIR Shut Off Valve is spring loaded and requires air pressure to open for air to flow. A leak in the hose between the AIR Pump and the AIR Shut Off Valve could cause a no flow condition even though the pump is flowing air.

A weak or worn AIR Pump might flow air but may not be able to overcome the spring in the AIR Shut Off Valve.

An AIR supply hose that is melted before the check valve could indicate exhaust gas back-flow past the check valve.

Low AIR System volume may cause a DTC P1415, P1416 or an intermittent complaint. Also check for the following conditions:
^ Pinched, kinked or restricted AIR pipes, hoses or fittings
^ Leaks, holes, loose fittings or hoses
^ Restricted or obstructed AIR Pump inlet hose
^ Worn or loose AIR Pump drive belt

Air flowing to the exhaust ports at the wrong time can cause a false lean HO2S indication and cause the VCM to add extra fuel. This will result in increased catalytic converter temperature, because more fuel and air will be oxidizing in the converter.

The AIR System is not completely noiseless. Under normal conditions noises rises in pitch as engine speed increases.

If excessive noise is caused by the AIR system, check for the following:
^ A seized AIR Pump
^ Proper mounting and bolt torque of the pump
^ Proper routing and connections of the hoses

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 Intermittents and Poor Connections Diagnosis. Symptom Related Diagnostic Procedures

Test Description
Number(s) below refer to step numbers on the Diagnostic Table
2. This step will determine if the AIR System is functioning correctly.
5. This step will ensure that the VCM is capable of turning the AIR Pump OFF.
15. This step will determine if the VCM is capable of controlling the AIR Pump Relay.
18. This step is to check for a short to voltage on the control circuit.
20. This step will determine if the pump is capable of flowing air.
21. This step is to check for a weak or worn AIR Pump. If the pump is weak it could flow air but may not be able to overcome the Shut Off Valve. Refer to Diagnostic Aids.
22. This step is to ensure that no leaks are found in the hose between the AIR Pump and the Shut Off Valve. The Shut Off Valve is spring loaded and requires air pressure to open for air to flow. A leak could prevent the valve from opening causing a no flow condition even though the pump is flowing air.
28. An open fuse for the ignition feed circuit could be caused by a short to ground in the components operated by the relay. Also check the wiring in the circuits on the switched side of the relay. Refer to Diagnostic Aids.