Chart C6A - Air Management Check
Air management is controlled by the air diverter and air switching valves, each with an ECM controlled vacuum solenoid. When the solenoid is grounded by the ECM, manifold vacuum will activate the valve and allow air pump air to be directed as follows:
- Air diverter solenoid not grounded by ECM - Air pump air diverted.
- Air diverter solenoid grounded by ECM - Air pump air to air switching valve.
- Air switching solenoid not grounded by ECM - Air pump air to converter.
- Air switching solenoid grounded by ECM - Air pump air to exhaust ports.
Loss of vacuum would cause air to be diverted to air cleaner.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- Air is directed to ports during open loop and engine starting. Engine always starts in open loop, even on a warm engine.
- Disconnect M/C solenoid. This should set a Code 23. When any code is set, the ECM opens ground circuit to air diverter valve. This checks ECM response to a fault. A ground in diverter valve circuit to ECM would prevent diverter valve action.
- This test checks for a grounded circuit to the ECM. Test light off is normal and indicates circuit is not grounded.
- This test checks for an open in the solenoid control circuits. Grounding test terminal should ground both solenoid circuits. Normally the test light should be on, which indicates problem is not in ECM or wiring. Problem is in solenoid valve or connections.
- This test checks for a grounded switching valve circuit. Test light off indicates circuit is okay and fault is in valve.