Pulsed Secondary Air Injection: Testing and Inspection

Chart C-6A:

Wiring Diagram:

CIRCUIT DESCRIPTION:

Air management is controlled by a switching valve and a bypass valve, each with an ECM controlled electrical solenoid valve. When the solenoid valve is grounded by the ECM, AIR pump pressure will activate the valve and allow pump air to be directed as follows:

^ Cold Mode - The switching solenoid valve is energized which in turn opens the port valve and allows flow to the exhaust ports.

^ Warm Mode - The switching solenoid valve is de-energized and the bypass solenoid valve is energized which closes the port valve and keeps the converter valve seated, thus forcing flow past the converter valve and to the catalytic converter.

^ Divert Mode - Both solenoid valves are de-energized, which opens the converter valve, allowing air to take the path of lease resistance, i.e., out the divert/relief tube to atmosphere.

TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.

1. This is a system functional check. Air is directed to ports during "Open Loop" and all engines start in "Open Loop" even on a warm engine. Since the air to the ports time is very short on some engines, prepare to observe port air prior to engine start up. On some engines, this can be done by squeezing a hose. On others, steel pipes have to be disconnected.

2. This should normally set a DTC 22. When any DTC is set, the ECM opens the ground to the AIR bypass valve and allows air to divert. This checks for ECM response to a fault. A ground in the AIR bypass valve circuit to the ECM would prevent divert action.

3. This checks for a grounded circuit to the ECM. Test light "OFF" is normal and would indicate the circuit is not grounded.

4. Checks for an open in the solenoid valve control circuits. Grounding the diagnostic "test" terminal should ground both solenoid valve circuits. Normally, the test light should be "ON" which indicates the problem is not in the ECM or wiring but at the solenoid connections or AIR bypass valve itself.

5. Checks for a grounded port (switching valve) solenoid valve circuit. Test light "OFF" would indicate the circuit is normal and fault is in the valve.